such as the cities, boroughs, towns, and villages in other States. Similarly, in New Jersey and Pennsylvania, where some townships possess powers and functions similar to those of incorporated places, the townships are not classified as "incorporated places." Thus some minor civil divisions which are "incorporated" in one legal sense of the word are not regarded by the Census Bureau as "incorporated places." Without this restriction all of the towns in the New England States, New York, and Wisconsin and the townships in New Jersey and Pennsylvania would be counted as incorporated places without any consideration of the nature of population settlement. A number of towns and townships in these States do qualify, however, as urban towns or townships and in others the densely settled portions are recognized as unincorporated places or as parts of an urban fringe.

In most States, the incorporated places form subdivisions of the minor civil divisions in which they are located. In other States, however, all or some of the incorporated places are them'selves also minor civil divisions. St. Louis, Baltimore, and 32 cities in Virginia (as of 1960) were independent of any county organization. In a number of instances such as Philadelphia, New Orleans, and San Francisco, the incorporated place is coextensive with the county in which it is located. New York City, on the other hand, is made up of five counties. An incorporated place may be located in two or more minor civil divisions or in two or more counties. Since, however, incorporated places are chartered by a State, no place can be located in two States, and adjoining places of the same name in two States are quite separate incorporations.

In the 1960 Census, 18,088 incorporated places were recognized (18,054 in conterminous United States). Of these places, 5,911 were cities, 1,214 were boroughs, 6,085 were towns, and 4,878 were villages. In addition, 125 urban towns and townships and 1 urban county were recognized as places. Of the 18,088 incorporated places, 9,874 had a population of less than 1,000; no separate data for the places under 1,000 are provided in the 1960 Housing reports. In the 1950 Census, 17,145 incorporated places were recognized (17,118 in conterminous United States), of which 9,843 had a population of less than 1,000.

As in the 1950 Census, the Bureau delineated, in advance of enumeration, boundaries for densely settled population centers without corporate limits. Each unincorporated place (designated in the tables by "U") possesses a definite nucleus of residences and has its boundaries drawn so as to include, if feasible, all the surrounding closely settled areas. In 1950, only those unincorporated places outside urbanized areas were recognized in the census. Incorporated places were identified whether inside or outside urbanized areas. In the 1960 Census, 1,576 unincorporated places of 1,000 inhabitants or more were recognized (1,528 in conterminous United States). In the 1950 Census, the corresponding count was 1,470 (1,430 in conterminous United States).

The figures for a given place apply to the housing within the boundaries of the place at the time of the census. Hence, the indicated change from 1950 to 1960 reflects the effect of any annexations or detachments. There were a great many annexations to cities in the decade of the 1950's, and some of them involved large areas. To permit an analysis of the importance of the change in boundaries, population figures for the 1950 area and for annexed areas of incorporated places are shown in table 9 in chapter A of the State parts of 1960 Census of Population, Volume I, Characteristics of the Population. For unincorporated places, the boundaries in many instances have changed as the communities have expanded.

URBANIZED AREAS

ban and rural housing in the vicinity of the larger cities, but individual urbanized areas have proved to be useful statistical areas also. They correspond to what are called "conurbations" in some other countries. An urbanized area contains at least one city of 50,000 inhabitants or more in 1960,1 as well as the surrounding closely settled incorporated places and unincorporated areas that meet the criteria listed below. An urbanized area may be thought of as divided into the central city, or cities, and the remainder of the area, or the urban fringe. All housing in an urbanized area is included in urban housing. Statistics for urbanized areas appear in the State chapters of Volume I. A map of each urbanized area in a State, if any, appears at the end of the State chapter, and the counties or parts of counties in which each area is located are listed on page 2 of the State chapter. In the 1960 Census, 213 urbanized areas were identified in the United States.

It appeared desirable to delineate the urbanized areas in terms of the 1960 Census results rather than on the basis of information available prior to the Census as was done in 1950. For this purpose a peripheral zone around each 1950 urbanized area and around cities that were presumably approaching a population of 50,000 was recognized. Within the unincorporated parts of this zone small enumeration districts were planned, usually including no more than one square mile of land area and no more than 75 housing units.'

Arrangements were made to include within the urbanized area those enumeration districts meeting specified criteria of population density as well as adjacent incorporated places. Since the urbanized area outside incorporated places was defined in terms of enumeration districts, the boundaries of the urbanized area for the most part follow such features as roads, streets, railroads, streams, and other clearly defined lines which may be easily identified by census enumerators in the field and often do not conform to the boundaries of political units.

In addition to its central city or cities, an urbanized area contains the following types of contiguous areas which together constitute its urban fringe:

1. Incorporated places with 2,500 inhabitants or more.

2. Incorporated places with less than 2,500 inhabitants, provided each has a closely settled area of 100 housing units or more. 3. Towns in the New England States, townships in New Jersey and Pennsylvania, and counties elsewhere which are classified as urban.

4. Enumeration districts in unincorporated territory with a population density of 1,000 inhabitants or more per square mile. (The areas of large nonresidential tracts devoted to such urban land uses as railroad yards, factories, and cemeteries were excluded in computing the population density of an enumeration district.)

5. Other enumeration districts in unincorporated territory with lower population density provided that they served one of the following purposes:

a. To eliminate enclaves.

b. To close indentations in the urbanized areas of one mile or less across the open end.

c. To link outlying enumeration districts of qualifying density that were no more than 11⁄2 miles from the main body of the urbanized area.

A single urbanized area was established for cities in the same standard metropolitan statistical area if their fringes adjoin. Urbanized areas with central cities in different standard metropolitan statistical areas are not combined, except that a

1 There are a few urbanized areas where there are "twin central cities" neither of which has a population of 50,000 or more but that have a combined population of at least 50,000. See the section below on "Standard metropolitan statistical areas" for further discussion of twin central

cities.

single urbanized area was established in the New York-Northeastern New Jersey Standard Consolidated Area and in the Chicago-Northwestern Indiana Standard Consolidated Area. Relation to earlier censuses.-Urbanized areas were first delineated for the 1950 Census. In 1950, urbanized areas were established in connection with cities having 50,000 inhabitants or more according to the 1940 Census of Population or a later census prior to 1950; in 1960, urbanized areas were established in connection with cities having 50,000 inhabitants or more according to the 1960 Census of Population. For the 1950 Census, 157 urbanized areas were identified (the identification being restricted to conterminous United States).

The boundaries of the urbanized areas for 1960 do not conform to those for 1950, partly because of actual changes in land use and density of settlement, and partly because of relatively minor changes in the rules used to define the boundaries. The changes in the rules were made in order to simplify the process of defining the boundaries; as a result of the changes, the area classified as urbanized tends to be somewhat larger than it would have been under the 1950 rules. The changes include the following:

1. The use of enumeration districts to construct the urbanized areas in 1960 resulted in a less precise definition than in 1950 when the limits were selected in the field using an individual city-type block as the unit of area added. On the other hand, the 1960 procedures produced an urbanized area based on the census results rather than an area defined about a year before the census, as in 1950.

2. Unincorporated territory was included in the 1960 urbanized area if it contained at least 1,000 persons per square mile, which is a somewhat different criterion from the 500 or more dwelling units per square mile of the included 1950 unincorporated areas. 3. The 1960 areas include those entire towns in New England, townships in New Jersey and Pennsylvania, and counties that are classified as urban in accordance with the criteria listed in the section on urban-rural residence. The 1950 criteria permitted the exclusion of portions of these particular minor civil divisions.

In general, however, the urbanized areas of 1950 and 1960 are based on essentially the same concept, and the figures for a given urbanized area may be used to measure the housing growth of that area.

Relation to standard metropolitan statistical areas.-Any city in an urbanized area which is a central city of a standard metropolitan statistical area (SMSA) is also a central city of the urbanized area. With but two exceptions, the names of the central cities appear in the titles of the areas. The central cities of the New York-Northeastern New Jersey Urbanized Area are the central cities of the New York, Newark, Jersey City, and Paterson-Clifton-Passaic Standard Metropolitan Statistical Areas. Likewise, the central cities of the Chicago-Northwestern Indiana Urbanized Area are the central cities of the Chicago and Gary-Hammond-East Chicago Standard Metropolitan Statistical

Areas.

The urbanized area can be characterized by the physical city as distinguished from both the legal city and the metropolitan community. In most cases, urbanized areas are smaller than SMSA's and are contained in SMSA's. However, in a few instances, the fact that the boundaries of SMSA's are determined by county lines and those of urbanized areas by the pattern of urban growth means that there are small segments of urbanized areas which lie outside SMSA's. In general, then, urbanized areas represent the thickly settled portions of SMSA's. Because of discontinuities in land settlement, there are also some cases in which a single SMSA contains several urbanized areas.

Areas crossing State lines.-Like standard metropolitan statistical areas, urbanized areas are not confined within State boundaries, nor within region or division boundaries. For urbanized areas which cross State lines, statistics are shown only in the

STANDARD METROPOLITAN STATISTICAL AREAS

It has long been recognized that for many types of analysis it is necessary to consider as a unit the entire area, in and around a city, in which the activities form an integrated economic and social system. Prior to the 1950 Census, areas of this type had been defined in somewhat different ways for different purposes and by various agencies. Leading examples were the metropolitan districts of the 1940 Census of Housing, the industrial areas of the Census of Manufactures, and the labor market areas of the Bureau of Employment Security. To permit all Federal statistical agencies to utilize the same areas for the publication of general-purpose statistics, the Bureau of the Budget has established "standard metropolitan statistical areas" (SMSA's). Every city of 50,000 inhabitants or more according to the 1960 Census of Population is included in an SMSA.

The definitions and titles of standard metropolitan statistical areas are established by the Bureau of the Budget with the advice of the Federal Committee on Standard Metropolitan Statistical Areas. This Committee is composed of representatives of the major statistical agencies of the Federal Government. The criteria used by the Bureau of the Budget in establishing the SMSA's are presented below. (See the Bureau of the Budget publication Standard Metropolitan Statistical Areas, U.S. Government Printing Office, Washington 25, D.C., 1961.)

The definition of an individual standard metropolitan statistical area involves two considerations: First, a city or cities of specified population to constitute the central city and to identify the county in which it is located as the central county; and second, economic and social relationships with contiguous counties which are metropolitan in character, so that the periphery of the specific metropolitan area may be determined.3 Standard metropolitan statistical areas may cross State lines.

Population criteria.-The criteria for population relate to a city or cities of specified size according to the 1960 Census of Population.

1. Each standard metropolitan statistical area must include at least:

a. One city with 50,000 inhabitants or more, or

b. Two cities having contiguous boundaries and constituting, for general economic and social purposes, a single community with a combined population of at least 50,000, the smaller of which must have a population of at least 15,000.

2. If each of two or more adjacent counties has a city of 50,000 inhabitants or more (or twin cities under 1b) and the cities are within 20 miles of each other (city limits to city limits), they will be included in the same area unless there is definite evidence that the two cities are not economically and socially integrated.

Criteria of metropolitan character.-The criteria of metropolitan character relate primarily to the attributes of the contiguous county as a place of work or as a home for a concentration of nonagricultural workers.

3. At least 75 percent of the labor force of the county must be in the nonagricultural labor force.*

4. In addition to criterion 3, the county must meet at least one of the following conditions:

a. It must have 50 percent or more of its population living in contiguous minor civil divisions with a density of at least 150

5

3 Central cities are those appearing in the standard metropolitan statistical area title. A "contiguous" county either adjoins the county or counties containing the largest city in the area, or adjoins an intermediate county integrated with the central county. There is no limit to the number of tiers of outlying metropolitan counties so long as all other criteria are met.

4 Nonagricultural labor force is defined as those employed in nonagricultural occupations, those experienced unemployed whose last occupation was a nonagricultural occupation, members of the Armed Forces, and new workers.

A contiguous minor civil division either adjoins a central city in a standard metropolitan statistical area or adjoins an intermediate minor civil division of qualifying population density. There is no limit to the number of tiers of contiguous minor civil divisions so long as the mini

persons per square mile, in an unbroken chain of minor civil divisions with such density radiating from a central city in the

area.

b. The number of nonagricultural workers employed in the county must equal at least 10 percent of the number of nonagricultural workers employed in the county containing the largest city in the area, or the county must be the place of employment of 10,000 nonagricultural workers.

c. The nonagricultural labor force living in the county must equal at least 10 percent of the number in the nonagricultural labor force living in the county containing the largest city in the area, or the county must be the place of residence of a nonagricultural labor force of 10,000.

5. In New England, the city and town are administratively more important than the county, and data are compiled locally for such minor civil divisions. Here, towns and cities are the units used in defining standard metropolitan statistical areas. In New England, because smaller units are used and more restricted areas result, a population density criterion of at least 100 persons per square mile is used as the measure of metropolitan character.

Criteria of integration.—The criteria of integration relate primarily to the extent of economic and social communication between the outlying counties and central county.

6. A county is regarded as integrated with the county or counties containing the central cities of the area if either of the following criteria is met:

a. Fifteen percent of the workers living in the county work in the county or counties containing central cities of the area,

or

b. Twenty-five percent of those working in the county live in the county or counties containing central cities of the area. Only where data for criteria 6a and 6b are not conclusive are other related types of information used as necessary. This information includes such items as average telephone calls per subscriber per month from the county to the county containing central cities of the area; percent of the population in the county located in the central city telephone exchange area; newspaper circulation reports prepared by the Audit Bureau of Circulation; analysis of charge accounts in retail stores of central cities to determine the extent of their use by residents of the contiguous county; delivery service practices of retail stores in central cities; official traffic counts; the extent of public transportation facilities in operation between central cities and communities in the contiguous county; and the extent to which local planning groups and other civic organizations operate jointly.

Criteria for titles. The criteria for titles relate primarily to the size and number of central cities.

7. The complete title of an SMSA identifies the central city or cities and the State or States in which the SMSA is located: a. The name of the standard metropolitan statistical area includes that of the largest city.

b. The addition of up to two city names may be made in the area title, on the basis and in the order of the following criteria:

(1) The additional city has at least 250,000 inhabitants. (2) The additional city has a population of one-third or more of that of the largest city and a minimum population of 25,000, except that both city names are used in those instances where cities qualify under criterion 1b. (A city which qualified as a secondary central city in 1950 but which does not qualify in 1960 has been temporarily retained as a central city.)

c. In addition to city names, the area titles will contain the name of the State or States in which the area is located. Inside and outside SMSA's.-Separate figures for housing units inside and outside SMSA's are provided for the United States as a whole, each region, and each geographic division in the United States Summary chapter, and for each State in the State chapters of Volume I. The statistics for housing units "inside SMSA's" for the total United States are for the total of the 212 SMSA's in the United States. Similarly, the statistics for "inside SMSA's" for a region, division, or State are for the total of the SMSA's, or parts of SMSA's, within the respective region, division, or State.

Statistics for each of the 212 SMSA's are provided in the State chapters of Volume I; and statistics for each of the 190 SMSA's of 100,000 inhabitants or more are provided in the United States Summary chapter. A map showing the location and boundaries of SMSA's within a State, if any, is included in the individual chapter for the State, and the constituent parts of the SMSA's are listed on page 2 of the respective State chapters. A map showing the location and names of all the SMSA's in the United States is included in the United States Summary chapter.

SMSA's crossing State lines. In the State chapters, data for SMSA's are shown in tables 12 to 17. For SMSA's that cross State lines, the full detail is shown in the chapter for each State in which a central city is located. In the State not containing a central city, the detail is shown only for the portion of the SMSA located in that State, with a total column for the portion in the other State (or States) and a total column for the entire SMSA. In table 1 of the State chapters, only the total for the entire SMSA and the portion for that State are given; in tables 8 and 36 to 42, the figures for the entire SMSA are shown in the chapter for each State containing part of an SMSA.

some areas.

Relation to earlier censuses.-In 1950, data were presented for standard metropolitan areas (SMA's) which were established in connection with cities of 50,000 inhabitants or more in 1950. In 1940, a somewhat similar type of area called the "metropolitan district" was used. In 1958, the criteria for delineating SMA's were revised by the Bureau of the Budget, and in 1959 the areas were designated as standard metropolitan statistical areas (SMSA's). In some cases, the 1960 SMSA has the same boundaries as the 1950 SMA; in others, parts have been added or deleted. The designation of the central cities also has changed for The relationship can be readily determined by comparing the 1960 and 1950 boundaries for the particular area. In 1950, a total of 168 standard metropolitan areas were identified in conterminous United States, and the Honolulu SMA was identified in Hawaii. A few of the 1950 SMA's were split into several SMSA's for 1960. Some entirely new SMSA's were added to the metropolitan territory of the existing SMA's; in terms of the 1950 counts, the net addition resulting from the designation of new metropolitan territory and changes in boundaries amounted to approximately 6 percent of the total units in the 1950 SMA's. In the text tables in the United States Summary chapter, 1950 data for "inside SMSA's" are for the 212 areas as defined for the 1960 Census; 1950 data for "in central cities" are for the central cities as defined for the 1960 SMSA's but with no adjustment for changes in city limits since 1950.

STANDARD CONSOLIDATED AREAS

In view of the special importance of the metropolitan complexes around New York and Chicago, the Nation's largest cities, several contiguous SMSA's and additional counties that do not appear to meet the formal integration criteria but do have strong interrelationships of other kinds have been combined into the New York-Northeastern New Jersey and Chicago-Northwestern Indiana Standard Consolidated Areas, respectively. The former is identical with the New York-Northeastern New Jersey SMA of 1950, and the latter corresponds roughly to the Chicago SMA of 1950 (two more counties having been added).

Data for the standard consolidated areas appear only in the chapters for New York and New Jersey and in the chapters for Illinois and Indiana. The constituent parts of the areas are listed on page 2 of the respective chapters. The New YorkNortheastern New Jersey Standard Consolidated Area comprises four SMSA's and two additional counties; the Chicago-Northwestern Indiana Standard Consolidated Area comprises two SMSA's.

The definitions and explanations of terms should be interpreted in the context of the 1960 Census procedures for collecting the data. Data were collected by a combination of self-enumeration, direct interview, and observation by the enumerator.

Items to be filled through self-enumeration appeared on forms which were supplied to households with the request that the household members themselves complete them. A few of the questions appeared on the Advance Census Report (ACR), which was to be filled and held until the enumerator called. Most of the questions, however, appeared on the Household Questionnaire, which was to be filled and mailed directly to the census office. In completing the self-enumeration items, the respondent had the explanations and wording that were printed on the forms. His answers were accepted unless the enumerator found it necessary to clarify or correct them.

If the self-enumeration form was not filled or if the answers were incomplete or inconsistent, the enumerator obtained the information through direct interview and recorded it directly on a FOSDIC schedule, a form specially designed for electronic data processing (see section on "Collection and processing of data"). The enumerator was instructed to read the questions from the FOSDIC Schedule and record the replies as given. If the respondent did not understand a question, the enumerator was to explain it based on his understanding of the definitions and instructions in the Enumerator's Reference Manuals. If the respondent's replies were incomplete or inconsistent, the enumerator was instructed to ask additional questions.

Information for vacant units was obtained by the enumerator largely from owners, landlords, neighbors, or other persons presumed to know the situation and the enumerator recorded the information directly on the FOSDIC schedules. A few items, including condition of unit, were always determined by the enumerator on the basis of his observation and, therefore, did not appear among the self-enumeration items.

The intent of the questions on the two types of forms is the same, although the wording of some of the questions and response categories on the direct-interview forms is briefer than on the self-enumeration forms. Furthermore, the direct-interview forms omit many of the instructions given on the self-enumeration forms. The differences, however, probably do not contribute in any important way to a lack of comparability of the data obtained from the two methods of enumeration. Through the use of the self-enumeration forms, respondents were given more uniform explanations of some of the questions than would have been possible in direct interview. On the other hand, the less detailed wording on the direct-interview forms was supplemented by the instructions given to the enumerator.

The questions and response categories used in self-enumeration compared with those used by the enumerator in direct interview are exhibited in the sections which follow. A general explanation appeared on the self-enumeration forms to the effect that the term "house" or "apartment" covered the house or part of the house the respondents occupied, or the apartment, flat, or rooms in which they lived. The explanation also pointed out that items on year built, sewage disposal, basement, and elevator in structure pertained to the whole building in which the respondents lived. In using the direct-interview forms, the enumerator was instructed to substitute an appropriate term for the word "unit," such as "house," "apartment," "flat," or "rooms." The proce dural instructions and the arrangement and sequence of the questions as they appeared on the forms are illustrated in the appendix to the United States Summary chapter of Volume I.

The Household Questionnaire was used only in areas where the twostage enumeration procedure was followed. In single-stage areas, these items were filled through direct interview. See section on "Collection

The definitions that follow conform to those provided in the Enumerator's Reference Manuals. They indicate the concept that was intended, whether the information was provided through self-enumeration or obtained by direct interview. Definitions from the 1950 and earlier censuses also indicate the concepts that were intended, with direct interview as the method of enumeration. Excerpts of instructions from the 1960 Enumerator's Reference Manuals are contained in the appendix to the United States Summary chapter of Volume I. For the most part, the excerpts do not include instructions for items to be filled by selfenumeration.

Instructions from the 1950 Enumerator's Reference Manual, and the schedule used in the enumeration, are reproduced in the appendix to the United States Summary chapter of 1950 Census of Housing, Volume I, General Characteristics.

Some of the definitions used in 1960 differ from those used in 1950 and earlier, as indicated below in the explanations of the items. These changes were made after consultation with users of housing census data to improve the statistics even though it was recognized that comparability would be affected. Statements on comparability with 1950 and earlier censuses do not always apply specifically to Alaska and Hawaii; the subjects and concepts applicable to the censuses in these two States are discussed in the section "Housing data for Alaska and Hawaii."

As in all surveys, there were some failures to execute the instructions exactly, regardless of the enumeration procedures applied, and some erroneous interpretations have undoubtedly gone undetected.

LIVING QUARTERS

Living quarters were enumerated as housing units or group quarters. Usually a housing unit is a house, apartment, or flat. However, it may be a trailer or a room in a hotel. A structure intended primarily for business or other nonresidential use may also contain a housing unit; for example, the rooms in a warehouse where the watchman lives, or the living quarters of a merchant in back of his shop. Group quarters are found in institutions, dormitories, barracks, rooming houses, and other places where the occupants do not have separate living arrangements.

Housing unit.-A house, an apartment or other group of rooms, or a single room is regarded as a housing unit when it is occupied or intended for occupancy as separate living quarters, that is, when the occupants do not live and eat with any other persons in the structure and there is either (1) direct access from the outside or through a common hall, or (2) a kitchen or cooking equipment for the exclusive use of the occupants of the unit. The occupants of a housing unit may be a family or other group of persons, or a person living alone.

Trailers, tents, boats, and railroad cars are included in the housing inventory if they are occupied as housing units. They are excluded if they are vacant, used only for extra sleeping space or vacations, or used only for business. Hotel accommodations are housing units if they are the usual residence of the occupants. Both vacant and occupied housing units are included in the housing inventory. Vacant quarters are excluded, however, if they are still under construction, being used for nonresidential purposes, unfit for human habitation, condemned, or scheduled for demolition (see section on "Vacant housing unit”).

Determination of housing unit.--Occupied living quarters were classified as housing units on the basis of information supplied by household members on the Advance Census Report (ACR) and questions asked by the enumerator where necessary. Identification of vacant housing units was determined by the enumerator, through observation and questions asked of the

a. Does more than one family live in this home?

b. (If yes) Do they live and eat with the family, or do they have separate quarters?

c. What is the name of the head of this household?

What are the names of all other
persons who live here?
(Before listing "other relatives"
or "nonrelatives," find out if
they have separate quarters.)

Determination by enumerator

d. Access to unit

Direct from outside or common hall.....

Through another unit..

Direct interview

e. Kitchen or cooking equipment

For exclusive use..

Shared or none.-------

f. Does anyone else live in this building or elsewhere on this property?

g. Are there any vacant apartments or any vacant rooms for rent?

h. (Ask about next unit) Name? No. of people? When home? (If vacant) Whom to see?

In filling the ACR, the respondent made the initial determination of the housing unit. The final determination was made by the enumerator as he followed the procedure outlined on the FOSDIC schedule. The decision as to what constituted a housing unit was made on the basis of the living arrangements of the occupants and not on relationship.

For

Some of the questions on the FOSDIC schedule parallel those on the self-enumeration form (ACR) as indicated below. these questions, the enumerator referred to the ACR for the answers. If only one family lived in the house, the enumerator regarded the quarters as one housing unit and no further probing was necessary to determine whether the quarters were "separate" quarters. (In such cases, direct access and separate cooking facilities were regarded as characteristics of the housing unit rather than criteria of separateness.) If there was evidence of additional separate quarters, such as a second mailbox or doorbell, or the presence of other relatives or nonrelatives, the enumerator was to determine whether there were additional housing units on the basis of either direct access or separate cooking facilities. Quarters that did not meet either criterion were not considered sufficiently separate to qualify as housing units. Quarters whose Occupants shared living arrangements were combined into one housing unit (unless the combined quarters contained five or more persons unrelated to the head, in which case the quarters were considered group quarters).

As a final step in the determination of separate housing units, the enumerator was instructed to take account of the respondent's answers to questions about other quarters on the property.

Living quarters are regarded as having direct access if the entrance is direct from the outside of the structure, or through a common hall, lobby, or vestibule used by the occupants of more than one unit. The hall, lobby, or vestibule must not be part of any unit, but must be clearly separate from all units in the structure. Living quarters have access through another unit when the only entrance to the room or rooms is through a room or hall which is part of the other unit.

A kitchen is defined as a room used primarily for cooking and the preparation of meals. Cooking equipment is defined as (1) a range or stove, whether or not it is regularly used, or (2) other equipment such as a hotplate or electrical appliance if it is used for the regular preparation of meals. Equipment is for exclusive use if it is used only by the occupants of one unit (see also section on "Exclusive or shared use"). Vacant units are considered to have cooking equipment if the last occupants had such equipment.

Hotel, motel.-Occupied rooms or suites of rooms in hotels, motels, and similar places are classified as housing units only when occupied by usual residents, i.e., persons who consider the hotel as their usual place of residence or have no usual place of residence elsewhere. Vacant rooms or suites of rooms are classified as housing units only in those hotels in which 75 percent or more of the accommodations are occupied by usual residents. The 75-percent limit is an arbitrary rule, the intent being to exclude from the housing inventory those quarters usually occupied by transient guests.

The distinction between hotels and rooming houses in the 1960 Census was made by the enumerator generally on the basis of local usage.

Kooming house, boarding house.-If any of the occupants in a rooming or boarding house have separate quarters and do not share living arrangements with other occupants in the structure, such quarters are considered separate housing units. The remaining quarters are combined. If the combined quarters contain four or fewer roomers unrelated to the head, they are classified as one housing unit; if the combined quarters contain five or more roomers unrelated to the head or person in charge, they are classified as group quarters. In a dormitory, residence hall, nurses' home, or similar place, living quarters of the supervisory staff are separate housing units if they satisfy the housing unit criteria; other living quarters are considered group quarters.

Institution.-Living quarters of staff personnel are separate housing units if they satisfy the housing unit criteria. Other living quarters are considered group quarters (see section on "Group quarters").

Comparability with earlier censuses.-In 1950, the unit of enumeration was the dwelling unit. Although the definition of "housing unit" in 1960 is essentially similar to that of "dwelling unit" in 1950, the housing unit definition was designed to encompass all private living quarters, whereas the dwelling unit definition did not cover all private living accommodations. In 1950, a dwelling unit was defined as (1) a group of rooms occupied or intended for occupancy as separate living quarters and having either separate cooking equipment or separate entrance; or (2) a single room occupied or intended for occupancy as separate quarters if (a) it had separate cooking equipment, (b) it was located in a regular apartment house, or (c) it constituted the only living quarters in the structure.

The main difference between housing units and dwelling units is in the treatment of one-room quarters. In 1960, separate living quarters consisting of one room with direct access but without separate cooking equipment qualify as a housing unit whether in an apartment house, rooming house, or house converted to apartment use. In hotels in 1960, a single room qualifies as a housing unit if occupied by a person whose usual residence is the hotel or a person who has no usual residence elsewhere; a vacant room (including quarters temporarily occupied by a nonresident) qualifies as a housing unit only if 75 percent or more of the accommodations in the hotel are occupied by usual residents. In 1950, a one-room unit without separate cooking equipment qualified as a dwelling unit only when located in a regular apartment house or when the room constituted the only living quarters in the structure. In hotels in 1950, occupied and vacant quarters that satisfied the dwelling unit criteria were included in the housing inventory only if more than half the accommodations in the hotel were for permanent guests; if less than half, none of the quarters were included in the housing inventory.

Data on access and cooking facilities of one-room quarters are given in 1960 Census of Housing, Volume II, Metropolitan Housing. As explained above, separate living quarters containing one room with direct access but having no separate cooking equipment were housing units in 1960 but would not have qualified as dwelling units by the 1950 definition unless they were located in a regular apartment house or were the only living quarters in the structure. Approximately one-half million occupied units, amounting to about 1 percent of the housing inventory in the United States as a whole, were 1-room units with