Except for the instances noted below, the concepts and definitions used in the quarterly surveys are identical with those used in the 1960 Census.

Standard metropolitan statistical area (SMSA).-Except in New England, an SMSA is a county or group of contiguous counties which contains at least one city of 50,000 inhabitants or more, or "twin cities" with a combined population of at least 50,000, the smaller of which must have at least 15,000. In addition to the county, or counties, containing such a city or cities, contiguous counties are included in an SMSA if, according to certain criteria, they are essentially metropolitan in character and are socially and economically integrated with the central city. In New England, SMSA's consist of towns and cities, rather than counties. A more detailed discussion of the criteria used to define SMSA's is given in 1960 Census of Housing, Volume I, States and Small Areas.

The statistics for inside SMSA's and outside SMSA's presented for the first quarters 1969 and 1968 relate to the areas (212) designated SMSA's at the time of the April 1960 Census. Prior to the second quarter 1962, the statistics related to the areas (168) designated SMA's at the time of the 1950 Census. For a list of the 212 SMSA's and their constituent parts, refer to the individual chapters (or Series HC(1) reports) in the 1960 Census of Housing, Volume I, States and Small Areas; or to the 1960 Census of Population, Volume I, Number of Inhabitants. For a list of the 168 areas and their constituent parts, refer to the individual chapters (or bulletins) in the 1950 Census of Housing, Volume I, General Characteristics; or to the 1950 Census of Population, Volume I, Number of Inhabitants, or Volume II, Characteristics of the Population, Part I, United States Summary.

Housing unit.--Beginning with the second quarter 1960, the 1960 Census housing unit concept was used to enumerate separate living quarters. Prior to that time, separate living quarters were enumerated according to the 1950 dwelling unit definition. The major difference between the two is not in content but in sharpening of the criteria by which separate units are identified. It is expected that the housing unit concept will yield better coverage of both occupied and vacant living quarters than the dwelling unit concept. Although no statistical measure of the effect of the change is available at this time, it is believed to be too small to affect the vacancy rates.

A group of rooms or a single room is regarded as a housing unit when it is occupied as separate living quarters, that is, when the oc

cupants 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.

Vacant living quarters intended for occupancy as separate living quarters and meet the physical criteria defined above are separate housing units. Because it is customary in some localities for occupants to furnish their own cooking equipment, vacant units without a kitchen or cooking equipment are considered to have such equipment if the last occupants had cooking equipment.

Living quarters of the following types are excluded from the housing unit inventory: Dormitories, bunkhouses, and barracks; quarters in predominantly transient hotels, motels, and the like, except those occupied by persons who consider the hotel their usual place of residence; quarters in institutions, general hospitals, and military installations except those occupied by staff members or resident employees who have separate living arrangements.

Quarters for roomers or boarders having shared living arrangements are excluded from the housing inventory if there are five or more such rooms; they are combined as one housing unit if there are four or fewer such rooms.

Trailers, tents, and boats are excluded if vacant, used for business, or used for extra sleeping space or vacations.

Dwelling unit, 1950.--The 1950 dwelling unit was defined as follows: A group of rooms occupied as separate living quarters was a dwelling unit if it had separate cooking equipment or if it constituted the only living quarters in the structure. Each apartment in a regular apartment house was a dwelling unit even though it may not have had separate cooking equipment. Apartments in residential hotels were dwelling units if they had separate cooking equipment or consisted of

two or more rooms.

Vacant quarters intended for occupancy as separate living quarters and met the physical criteria defined above were separate dwelling units. Vacant units were considered as having cooking equipment if they were equipped with such equipment or if the last occupants had cooking equipment.

In general, living quarters of the types excluded from the housing unit inventory were excluded from the dwelling unit inventory.

Occupied housing units.-- A housing unit is occupied if a person or group of persons was living in it at the time of enumeration or if the occupants were only temporarily absent, as for example, on vacation. The persons living in the unit must consider it their usual place of residence or have no usual place of residence elsewhere. The count of occupied housing units is the same as the count of households.

Units occupied by persons with usual residence elsewhere.-- A housing unit which is occupied temporarily by persons who usually live elsewhere is enumerated as a vacant unit provided the usual place of residence is held for the household and is not offered for rent or for sale. For example, a beach cottage occupied at the time of enumeration by a family which has a usual place of residence in the city is included in the count of vacant units. Their house in the city would be reported "occupied" and would be included in the count of occupied units since the occupants are only temporarily absent.

Units occupied by persons with usual residence elsewhere are included with seasonal units or with year-round vacant units as dilapidated, or not dilapidated but held off the market, as the case may be.

Vacant housing units.--A housing unit (furnished or unfurnished) is vacant if no persons were living in it at the time of enumeration, except when its occupants were only temporarily absent. Dilapidated vacant units were included if they were intended for occupancy as living quarters; however, if the vacant unit was unfit for use and beyond repair so that it was no longer considered living quarters, it was excluded from the inventory. Vacant units to be demolished were excluded if unfit or if there was positive evidence, such as a sign or mark on the house or in the block, that the unit was to be torn down. New units not yet occupied were enumerated as vacant housing units if construction had proceded to the point that all the exterior windows and doors were installed and final usable floors were in place; otherwise, potential units under construction were not included. Unoccupied units held off the market for various reasons and units recently rented or sold but not yet occupied are considered vacant.

Vacant sleeping rooms in lodginghouses, transient accommodations, barracks, and other quarters not defined as housing units are not included in the statistics in this report. (See section on "Housing unit.")

Year-round vacant units.--Year-round units are those intended for occupancy at any time of the year, even though they may not be in use the year round. In resort areas, a housing unit which

is usually occupied on a year-round basis was considered a year-round unit. On the other hand, a housing unit located in the closely built-up area of a nonresort city was considered a "year round" unit even though it may be occupied only part of the year. As indicated above, year-round units temporarily occupied by persons with usual residence elsewhere are included with year-round vacant units.

Seasonal vacant units.--Seasonal housing units are those intended for occupancy during only a season of the year and are found primarily in resort areas. In farm areas, housing units used for only a portion of the year to house migratory workers employed during the crop season are classified as seasonal.

Seasonal units comprise unoccupied seasonal units and seasonal units temporarily occupied by persons with usual residence elsewhere. Units in resort areas occupied by persons who considered the unit their usual place of residence or had no other place of residence are classified as occupied. (See also section on "Occupied housing units.")

Available vacant units.--The categories "available for rent" and "available for sale only" provide a measure of vacant housing units which are on the market for year-round occupancy, are in either sound or deteriorating condition, and are being offered for rent or for sale.

To describe the rental and sale market, the measure of units available for rent is expressed as a percentage of the total rental inventory and the measure of units available for sale is expressed as a percentage of the total homeowner inventory. In the analysis of the total inventory and total vacant units, percentages are based on total housing units.

Beginning with this report, additional measures are given which describe the available vacancy supply in terms of selected characteristics of the rental and homeowner inventories. Vacancy ratios are provided by monthly rent levels, asking price, year built, number of rooms, number of units in structure, and plumbing facilities.

Vacant units available for rent.--This group consists of available vacant units offered for rent and those offered "for rent or sale."

Vacant units available for sale only.--This group is limited to units for sale only; it excludes units "for rent or sale." If a unit was located in a multiunit structure which was for sale as an entire structure and if the unit was not for rent, it was reported as "held off market." However, if the individual unit was intended to be occupied by the new owner, it was reported as for sale.

Vacant units rented or sold.--This group consists of year-round vacant units in sound or deteriorating condition which have been rented or sold but the new renters or owners have not moved in as of the day of enumeration. In the 1950 statistics, such units are shown in combination with year-round not dilapidated vacant units held off the market.

Vacant units held off the market.--Included in this category are year-round units in sound or deteriorating condition which were vacant for reasons other than those mentioned above: For example, held for occupancy of a caretaker, janitor, and the like; held for settlement of estate; held for personal reasons of the owner; and temporarily occupied by persons who have a usual place of residence elsewhere. In the 1950 statistics, such units are shown in combination with year-round not dilapidated vacant units, rented or sold, as "nonseasonal not dilapidated, not for rent or sale" units.

Rental vacancy rate.--The percentage relationship of the vacant units available for rent to the total rental inventory is termed the rental vacancy rate. It is computed by dividing the number of vacant units available for rent by the total rental units. The total rental units consist of the renter-occupied units, vacant units rented but not yet occupied at the time of enumeration, and the vacant units available for rent. Vacant units that are dilapidated, seasonal, or held off the market are excluded.

Homeowner vacancy rate.--The percentage relationship between the vacant units available for sale and the total homeowner inventory is termed the homeowner vacancy rate. It is computed by dividing the number of vacant units available for sale by the total homeowner units. The total homeowner units consist of the owner-occupied units, vacant units sold and awaiting occupancy, and the vacant units available for sale. Vacant units that are dilapidated, seasonal, or held off the market are excluded.

Vacancy rates by selected characteristics.-These ratios express the relationship between subclasses of vacant available housing units and rental and homeowner units that have a common characteristic.

Selected vacancy rates in rental units are computed by dividing the number of available vacant for-rent units in the specified category by the total rental units in that group. The total rental units consist of the renter-occupied units and the vacant for-rent units with the common characteristic. Similarly, vacancy rates in specific types of homeowner units are computed by dividing the total number of vacancies for sale

For a more detailed explanation on condition of housing, see Series H-111 reports for previous quarters. Also, see 1960 Census of Housing, Volume I, States and Small Areas.

A

Number of rooms.--All rooms which are used, or are suitable for use, as living quarters were counted in determining the number of rooms in the housing unit. Included are kitchens, bedrooms, dining rooms, living rooms, and permanently enclosed sunporches of substantial size; and finished basement or attic rooms, recreation rooms, suitable for use as living quarters. kitchenette or half-room which is partitioned off from floor to ceiling was counted as a separate room, but a combined kitchenette and dinette separated only by shelves or cabinets was counted as only one room. Not counted as rooms were bathrooms, strip or pullman kitchens, halls or foyers, alcoves, pantries, laundries, closets or storage space, and unfinished basement or attic rooms not suitable for living quarters.

The median number of rooms is the theoretical value which divides the housing units equally, one-half having more rooms and one-half having fewer rooms than the median. In the computation of the median, a continuous distribution was assumed. For example, when the median was in the 3-room group, the lower and upper limits were assumed to be 2.5 and 3.5, respectively. Tenths were used in the computation of the median to permit comparisons.

Number of bedrooms. --Only rooms intended primarily to be slept in were counted as bedrooms. A bed-living room or a den intended primarily for purposes other than sleeping was not counted as a bedroom. A 1-room apartment, therefore, was reported as having no bedroom.

Number of housing units in structure.--A structure either stands by itself or has vertical walls dividing it from all other structures. The count of housing units in a structure is the total number of units in the structure, including both occupied and vacant units. A structure may be detached, attached, or semidetached. A detached structure has open space on all four sides; an attached structure is one of a row of three or more adjoining structures, or is a structure attached to a nonresidential structure; while a semidetached structure is one of two adjoining residential structures, each with open space on the remaining three sides. In apartment developments, each building with open space on all sides is considered a separate structure. In the tabulations, occupied trailers are included in the category "one-housing-unit" in structure.

The statistics reflect the number of housing units in the structure in which they are located,

rather than the number of residential structures. In the quarterly surveys, data were obtained on the number of housing units in the structure, regardless of the type of structure (detached, attached, or semidetached) in which the unit was located.

Year structure built.--"Year built" refers to the date the original construction of the structure was completed, and not to any later remodeling, addition, or conversion. The figures on the number of units built during a given period relate to the number of units in existence at the time of enumeration. The figures reflect the number of units constructed during a given period plus the number created by conversions in structures originally built during that period, minus the number lost in structures built during the period. Losses occur through demolition, fire, flood, disaster; change to nonresidential use; or merger to fewer housing units.

Data on year built are more susceptible to errors of response and nonreporting than data on many of the other items. In most cases, the information was given according to memory or estimates of the occupants of the structure or of other persons who had lived in the neighborhood a long time.

Duration of vacancy.-- The length of time a housing unit was vacant was computed from the day the unit became vacant until the day of enumeration. It should be noted that the time period is not the total time a unit has been in a particular vacancy status, but it is the duration of vacancy up to the day of enumeration. For newly constructed units, it represents the time period since the date when the unit was considered a vacant housing unit, that is, when construction had reached the point that all exterior windows and doors were installed and final usable floors were in place.

The time intervals used in the tables represent full months, calculated from a date in the month to the same date the following months. For example, if the unit became vacant on January 29 and was still vacant on the day of enumeration, March 20, the time reported would be "1 up to 2 months," meaning that the unit had been vacant for more than 1 month but less than 2 months. Or if the unit became vacant on February 25 and was still vacant on March 20, the time reported would be "less than 1 month."

Plumbing facilities.--Housing units "with all facilities" consist of those which have: Both a flush toilet and a bathtub or shower inside the structure for the exclusive use of the intended occupants of the unit, and hot running water.

Units "lacking facilities" consist of those which lack one or more of the plumbing facilities or which lack exclusive use of these facilities.

Facilities were considered "inside the structure" if they were located within the housing Facilities unit or elsewhere in the structure. are for exclusive use if they are used, or intended for use, by only the occupants of one housing unit.

A housing unit was considered as having hot running water whether it was available the year round or only part of the time. For example, hot running water may be available only during the heating season or at various times during the week.

Contract rent.-- For renter-occupied units, the contract rent is the monthly rent agreed upon regardless of any furnishings, utilities, or services that may be included. For vacant units, rent is the amount asked for the unit at the time of enumeration; the amount may differ from the rent contracted for when the unit is occupied. As in the 1960 Census, the statistics exclude rents for renter-occupied farm housing units in rural territory and rents for vacant units on places of 10 acres or more in rural areas. The statistics in the reports for 1960 or earlier exclude rental vacancies in rural areas which were classified as farm by the 1950 definition (the classification depending on the reply to the question "Is this house on a farm or ranch?”). Data for such units are excluded because of the difficulty of separating the rental for the housing unit from the rental for the land.

The median monthly rent is the rent which divides the series into two equal parts, one-half of the units with rents higher than the median and the other half with rents lower than the median. In the computation of the median, a continuous distribution was assumed; and the limits of the class intervals were assumed to stand at the midpoints of the 1-dollar interval between the end of one of the rent groups and the beginning of the next. For example, the limits of the interval designated $30 to $39 were assumed to be $29.50 and $39.50.

Inclusion of utilities in rent.-- The utilities included in the inquiry were heat, light, cooking fuel, and water. The statistics reflect whether all or not all of these utilities are provided for in the amount of rent asked at the time of enumeration, not what could be provided for more or less rent. Data on the inclusion of utilities are limited to the vacant units for which rent is reported. No data on utilities are collected for renter-occupied units.

Value.--Value is the respondent's estimate of how much the property would sell for on the current market. For vacant units, value is the sale price asked for the property at the time of enumeration and may differ from the price at which the property is sold. Statistics on value for owner-occupied units and sale price asked for vacancies available for sale are limited to units in 1-housing unit structures, without business, and with only one housing unit on the property. Statistics on value also exclude occupied trailers.

As in the 1960 Census, the statistics in this report are for owner-occupied and vacant forsale units in urban areas and those in rural areas which are located on places of less than 10 acres; thus units in rural areas on places of 10 acres or more are excluded. The statistics in the reports for 1960 or earlier exclude homeowner vacancies in rural areas which were classified as farm by the 1950 definition (the classification depending on the reply to the question "Is this house on a farm or ranch?”). Data for such units are excluded because they would reflect varying amounts for land, business uses, or for more than one housing unit on the property.

The median value or sale price is the amount which divides the series into two equal parts, onehalf of the units with values higher than the median and the other half with values lower than the median. The median was computed on the basis of more detailed tabulation groups than are shown in the tables and was rounded to the nearest hundred dollars.

Urban-rural residence.--The territory classified as urban is the same as that in the 1960 Census. Urban housing comprises all units in (a) places of 2,500 inhabitants or more incorporated as cities, boroughs, villages, and towns (except towns in New England, New York, and Wisconsin); (b) the densely settled urban fringe, whether incorporated or unincorporated, of urbanized areas; (c) towns in New England and townships in New Jersey and Pennsylvania which contain no incorporated municipalities as subdivisions and have either 25,000 inhabitants or more or a population of 2,500 to 25,000 and a density of 1,500 persons or more per square mile; (d) counties in States other than the New England States, New Jersey, and Pennsylvania that have no incorporated municipalities within their boundaries and have a density of 1,500 persons or more per square mile; and (e) unincorporated places of 2,500 inhabitants or more. maining units are classified as rural.

The re