Rental vacancy rate.-The percentage relationship between vacant units available for rent and the total rental inventory is termed the rental vacancy rate. The total rental inventory consists of renter-occupied units and vacant units available for rent. This rate more adequately describes rental market conditions than a rate based on total housing units.

Duration of vacancy (H38).--The duration of vacancy is the length of time (in months) from the date the last occupants moved from the unit to the date of enumeration. The data, therefore, do not provide a direct measure of the total length of time. units remain vacant. For newly constructed units which have never been occupied, the duration of vacancy represents the time period since the date construction was completed.

No information on duration of vacancy was collected in previous censuses.

Acres in the place (H17). --Data on number of acres in the place are presented for vacant units in rural territory. The categories are "10 acres or more" and "less than 10 acres" (see section on "Farm-nonfarm residence").

Farm-nonfarm residence (H17, H18, H42).-In rural territory, occupied housing units are subdivided into rural-farm and rural-nonfarm units on the basis of number of acres in the place and total sales of farm products in 1959. All vacant units are included in the rural-nonfarm inventory. Number of acres in the place was reported for vacant units but no information was obtained on sales of farm products.

Occupied housing units are classified as farm units if they are located on places of 10 or more acres from which sales of farm products amounted to $50 or more in 1959, or on places of less than 10 acres from which sales of farm products amounted to $250 or more in 1959. The remaining occupied units, including those on "city lots," are classified as nonfarm units. (A house is on a city lot if it is located in a community or closely built-up area and the "place" is no larger than the house and yard.) Occupied units for which cash rent is paid also are classified as nonfarm if the rent does not include any land used for farming, even though the place on which the unit is located qualifies as a farm.

For purposes of determining farm residence, the residential "place" consists of the land which the respondent considers to be the farm, ranch, or property. The place may consist of more than one tract of land; the tracts are usually adjoining although they may be separated by a road, creek, or another piece of land. If there is more than one house on the place, all have the same farm-nonfarm classification (except that, on farms, units for which cash rent is paid are always classified as nonfarm if the rent does not include any land used for farming). For example, if the owner lives in one house and a hired hand lives in a separate house on the same place, both housing units have the same classification.

Sales of farm products refer to the total amount (gross amount) received from the sale of crops, vegetables, fruits, nuts, livestock and livestock products (milk, wool, etc.), poultry and poultry products, and nursery and forest products produced on the place and sold at any time during 1959.

Farm - nonfarm residence in 1950 was determined for both occupied and vacant units in rural territory by the respondent's answer to the question, "Is this house on a farm or ranch?" Units on farms whose occupants paid cash rent for the house and yard only were classified as nonfarm, similar to the procedure in 1960. Units on institutional grounds and in summer camps and tourist courts were classified as nonfarm in 1950, regardless of the answer to the above question. Housing units in such places in 1960 are classified according to

In the 1950 and earlier censuses, a count of farm units in cities and other urban territory was obtained, but in 1960 no effort was made to identify urban-farm housing. In 1950, the count of urban-farm units (occupied and vacant) amounted to only about 96,000 units in the country as a whole.

The definition adopted for 1960 employs more restrictive criteria than the 1950 definition. One reason for the change was to make the definition of farm residence essentially consistent with the definition of a farm used in the agricultural census, beginning with the 1959 Census of Agriculture. The effect of the 1960 definition is to exclude from the farm inventory, housing units located on places considered as farms by the occupants but from which agricultural products are not sold or from which sales are below a specified minimum. On the other hand, the 1960 definition brings into the farm inventory a smaller group of housing units which meet the criteria but which are not considered by the occupants to be located on farms.

A test conducted in the Census Bureau's Current Population Survey in March 1960 showed that an estimated 1.4 million rural occupied units (households) in the United States would have been classified as "farm" under the 1950 definition but as “nonfarm” under the 1960 definition; conversely, about 0.4 million rural occupied units would have been classified as "nonfarm" under the 1950 definition but as "farm" under the 1960 definition. The net reduction of 1.0 million units represented approximately one-fifth of the occupied farm housing under the 1950 definition. No similar estimates of the proportionate reduction are available by State or smaller area. The impact of the change in definition has probably been very uneven from one area to another.

Farm residence was determined in the 1940 Census of Housing also. Counts of farm "families" are available for each of the census years from 1930 back to 1890. Comparability is affected not only by the change in the definition of farm residence but also by the change in the delineation of urban and rural territory.

STRUCTURAL CHARACTERISTICS

The comparison of the wording and explanations that appeared on the self-enumeration and direct-interview forms is given below. Type of housing unit and number of units in structure were always to be determined by the enumerator through observation and supplementary questions asked of the respondent. Number of rooms appeared as a selfenumeration item on the Advance Census Report, and all the other self-enumeration items appeared on the Household Questionnaire, which was used in two-stage areas. The direct-interview questions appeared on a FOSDIC schedule. Although the question on year built appeared on the self-enumeration form, the enumerator was instructed to obtain this information from the resident owner, manager, or janitor if the unit was in a structure containing five housing units or more.

Rooms (H8).-The number of rooms is the count of whole rooms used for living purposes, such as living rooms, dining rooms, bedrooms, kitchens, finished attic or basement rooms, recreation rooms, lodgers' rooms, and rooms used for offices by a person living in the unit. Not considered as rooms are bathrooms; halls, foyers, or vestibules; closets; alcoves; pantries; strip or pullman kitchens; laundry or furnace rooms; unfinished attics, basements, and other space used for storage; porches, unless they are permanently enclosed and suitable for year-round use; and offices used only by persons not living in the unit. A partially divided room, such as a dinette next to a kitchen or living room, is considered as a separate room if there is a partition from floor to ceiling. Rooms equipped with movable partitions

by the number of owner- or renter-occupied units, respectively. The tabulation form contained a terminal category of "10 or more" rooms. For purposes of the computation, the terminal category was given a mean value of 11.

The 1960 data on number of rooms are considered directly comparable with 1950 and 1940 data, since essentially the same definitions were used in all three cen

suses.

Bedrooms (H19).- The number of bedrooms is the count of rooms used mainly as bedrooms. In addition to regular bedrooms, the count includes studies, dens, enclosed porches, finished attics, guest rooms, or other extra rooms if they are currently used principally and regularly for sleeping. Rooms used only occasionally for sleeping, such as a living room with a hideaway bed, were not to be counted as bedrooms. A housing unit consisting of only one room, such as a one-room efficiency apartment, was to be reported as having no bedroom.

Information about the number of bedrooms was not collected in the 1950 or 1940 Censuses.

Year structure built (H20).-"Year built" refers to the date the original construction of the structure was completed, not to any later remodeling, addition, or conversion.

The figures on the number of units built during a given period do not necessarily represent the number of housing units added to the inventory during that period. 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, and conversion to nonresidential use or 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.

Statistics in this report on the number of new units, according to the data on year built, may differ from figures on new construction collected in the Components of Inventory Change program which employed specialized procedures for collecting the data. (Statistics on new construction units for selected SMSA's and the United States are published in 1960 Census of Housing, Volume IV, Components of Inventory Change.)

Data on year built were collected in the 1950 and the 1940 Censuses of Housing also. While the definitions were the same in the three censuses, comparability of the data may be affected by relatively large reporting errors.

Units in structure (H29).-In determining the number of units in the structure, the enumerator was instructed to count both occupied and vacant housing units, but not business units or group quarters. A structure is defined as a separate building that either has open space on all four sides, or is separated from other structures by dividing walls that extend from ground to roof. Structures containing only one housing unit were further classified as detached or attached.

A 1-unit detached structure has open space on all four sides and contains only one housing unit. Such a structure is considered detached even though it has an adjoining shed or private garage or contains a business unit. A 1-unit attached structure contains only one housing unit and has one or more walls extending from ground to roof separating it from adjoining structures. For row houses, double houses,

is a separate attached structure if the dividing or common wall goes from ground to roof.

Statistics are presented in terms of number of housing units rather than number of residential structures. The number of structures for some of the categories, however, is apparent. For housing units in 1-unit structures, the number of housing units and the number of structures are the same. The number of housing units in 2-unit structures is twice the number of structures. For the remaining categories, the number of structures cannot be ascertained from the data as tabulated.

The categories for number of housing units in the structure in 1960 are not directly comparable with those in 1950, particularly for 1- and 2-unit structures. In 1950, units in detached or attached structures were shown separately, but those in semidetached structures containing 1 or 2 units were combined into one category. ("Semidetached" structures of 1950 are defined as "attached" in 1960.) Comparability between 1950 and 1960 data may also be affected by the change in concept from dwelling unit to housing unit.

In the 1940 Census, data were provided on number of residential structures as well as number of units in a structure. The 1940 definitions were basically the same as in 1960 with a few exceptions. Principally, each unit classified as "2-family side-by-side" in 1940 would be classified as "1-unit attached" according to the 1960 definition; and units in structures containing a business and having one to four units comprised a separate category in 1940.

Trailer (H3, H37).-Trailers occupied as living quarters are included in the housing inventory. When one or more rooms have been added to a trailer, however, it is classified as "house, apartment, flat." A trailer is "mobile" if it rests on wheels or on a temporary foundation, such as blocks or posts. A trailer is "on a permanent foundation" if it is mounted on a regular foundation of brick, stone, concrete, etc. When trailers are not shown as a separate category in a table, they are included with units in 1-unit

structures.

In 1950, only occupied trailers on wheels or on temporary foundations were identified. A trailer on a permanent foundation or with a room added was classified as "house, apartment, flat." In 1940, occupied trailers were combined with tents, boats, railroad cars, and shacks in the published data. Basement (H33).- Statistics on basements are presented in terms of the number of housing units located in structures built with a basement, on a concrete slab, or in another way. "Basement" is defined as enclosed space beneath all or part of a structure, accessible to the occupants and of sufficient depth so that an adult can walk upright. Units built on a "concrete slab" have no basement and no crawl space or air space below the first floor. The category "other" includes units in structures resting on posts, those built directly on the ground, and those having only crawl space under the building to provide ventilation or accessibility for service or repairs.

No question about basements was asked in censuses prior to 1960.

Elevator in structure (H34).-Statistics on elevator in structure are presented in terms of the number of housing units located in structures with four stories or more, not counting the basement. Units are classified "with elevator" if they are located in a building with an elevator which passengers may use. Units are in a "walkup" structure if the structure has no passenger elevator or if the only elevator service is for freight. Data on elevators are published only for large places, that is, places which had a population of 50,000 or more in 1950 or in an interim

or more in 1960. The data are not given in the State reports; a table for all such places in the United States appears in the United States Summary part of 1960 Census of Housing, Volume I, States and Small Areas.

Data on elevators were not collected in earlier censuses.

CONDITION AND PLUMBING FACILITIES

The questions on condition and plumbing are shown below. Water supply, toilet facilities, and bathing facilities appeared as self-enumeration items on the Advance Census Report and the remaining three self-enumeration items appeared on the Household Questionnaire, which was used in two-stage areas. The direct-interview questions appeared on a FOSDIC schedule. Condition of the unit, however, was determined by the enumerator on the basis of his observation; the respondent was not be questioned about the condition of his living quarters.

Condition and plumbing combined.-Both the condition of a housing unit and the type of plumbing facilities are considered measures of the quality of housing. Categories representing various levels of housing quality have been established by presenting the items in combination.

To measure condition, the enumerator classified each housing unit in one of three categories: sound, deteriorating, or dilapidated. The plumbing facilities that are combined with condition are: water supply, toilet facilities, and bathing facilities.

The category "with all plumbing facilities" consists of units which have hot and cold water inside the structure, and flush toilet and bathtub (or shower) inside the structure for the exclusive use of the occupants of the unit.

Units "lacking only hot water" have all the facilities except hot water. Units "lacking other plumbing facilities" may (or may not) have hot water but lack one or more of the other specified facilities. Also included in this category are units having no piped water inside the structure and units whose occupants share toilet or bathing facilities with the occupants of another housing unit. The combination of "lacking only hot water" and "lacking other plumbing facilities" is presented as "lacking some or all facilities" in some of the distributions.

In the distribution of plumbing facilities for vacant available, units, the figures apply only to sound and deteriorating units. Data for dilapidated vacant units are not shown separately, but are included in the distribution for "all units."

Condition and plumbing facilities were combined in the 1950 reports also. If the 1960 categories of sound and deteriorating are combined, the category "with all plumbing facilities" compares with the 1950 category "not dilapidated, with private toilet and bath, and hot running water"; the 1960 "lacking only hot water" compares with the 1950 “not dilapidated, with private toilet and bath, and only cold water"; and the 1960 "lacking other plumbing facilities" compares with the 1950 combination of "not dilapidated, with running water, lacking private toilet or bath" and "not dilapidated, no running water."

Condition (H6).-The enumerator determined the con dition of the housing unit by observation, on the basis of specified criteria related to the extent or degree of visible defects. The types of defects the enumerator was to look for are associated with weather tightness, extent of disrepair, hazards to the physical safety of the occupants, and inadequate or makeshift construction. These are signs of other structural defects which may be hidden. Defects which would be revealed only by a more careful inspection than is possible during a census, such as the presence of

CONDITION

Observation by enumerator

H6. Condition

Sound...

Deteriorating. Dilapidated..

WATER SUPPLY, TOILET AND BATHING FACILITIES, BATHROOMS

Self-enumeration

Direct interview

H9. Is there hot running water (for this unit)?

Running water in structure:

Hot and cold..
Cold only....

Run. water outside.
No running water.

H10. Is there a flush toilet (for this unit)?

For exclusive use.. Shared...

None...

H11. Is there a bathtub or shower (for this unit)?

For exclusive use. Shared.

None..

H30. How many bathrooms are in this unit?

None or partial only.

1..

1 and partial.

2 or more......

00 00

H31. What is the source of water? Public system (or private company).

Individual well. Other.......

H32. Is the house connected to a public sewer?

Public sewer..

Septic tank or cesspool.. Other...

0 00

are not included in the criteria for determining the condition of a unit.

Sound housing is defined as that which has no defects, or only slight defects which normally are corrected during the course of regular maintenance. Examples of slight defects are: lack of paint; slight damage to porch or steps; slight wearing away of mortar between bricks or other masonry; small cracks in walls, plaster or chimney; cracked windows; slight wear on floors, door sills, doorframes, window sills, or window frames; and broken gutters or downspouts.

Deteriorating housing needs more repair than would

housing has one or more defects of an intermediate nature that must be corrected if the unit is to continue to provide safe and adequate shelter. Examples of intermediate defects are: holes, open cracks, rotted, loose, or missing materials over a small area of the foundation, walls, roof, floors, or ceilings; shaky or unsafe porch, steps, or railings; several broken or missing windowpanes; some rotted or loose window frames or sashes that are no longer rainproof or windproof; broken or loose stair treads, or broken, loose, or missing risers, balusters, or railings of inside or outside stairs; deep wear on door sills, doorframes, outside or inside steps or floors; missing bricks or cracks in the chimney which are not serious enough to be a fire hazard; and makeshift chimney such as a stovepipe or other uninsulated pipe leading directly from the stove to the outside through a hole in the roof, wall, or window. Such defects are signs of neglect which lead to serious structural deterioration or damage if not corrected.

Dilapidated housing does not provide safe and adequate shelter and in its present condition endangers the health, safety, or well-being of the occupants. Such housing has one or more critical defects; or has a combination of intermediate defects in sufficient number or extent to require considerable repair or rebuilding; or is of inadequate original construction. The defects are either so critical or so widespread that the structure should be extensively repaired, rebuilt, or torn down.

Critical defects result from continued neglect or lack of repair, or indicate serious damage to the structure. Examples of critical defects are: holes, open cracks, or rotted, loose, or missing material (clapboard siding, shingles, bricks, concrete, tile, plaster, or floorboards) over a large area of the foundation, outside walls, roof, chimney, or inside walls, floors, or ceilings; substantial sagging of floors, walls, or roof; and extensive damage by storm, fire, or flood.

To be classified as dilapidated on the basis of intermediate defects, a housing unit must have such defects in sufficient number or extent that it no longer provides safe and adequate shelter. No set number of intermediate defects is required.

Inadequate original construction includes: shacks, huts, or tents; structures with makeshift walls or roofs, or built of packing boxes, scrap lumber, or tin; structures lacking foundations (walls rest directly on the ground); structures with dirt floors; and cellars, sheds, barns, garages, or other places not originally intended for living quarters and inadequately converted to such use.

The enumerator was provided with detailed written instructions and with photographs illustrating the levels of condition. In addition, audio-visual techniques were used in training the enumerator. A filmstrip of photographs in color depicted various types of defects and a recorded narrative explained how to determine the classification of condition on the basis of these defects. (Photographs and instructions from the Enumerator's Reference Manual are reproduced in the United States Summary part of 1960 Census of Housing, Volume I, States and Small Areas.)

The enumerator was instructed to judge each unit on the basis of its own characteristics, regardless of the neighborhood, age of the structure, or the race or color of the occupants. He was cautioned, for example, that although lack of paint is only a slight defect, this and other signs of neglect are warnings to look closely for more serious defects. Also, exterior covering may improve the appearance of a structure but not its condition, and the sturdiness of brick or other masonry walls can be misleading if there are defects in other parts of the structure.

In judging condition, the enumerator was instructed to

If the unit was "not dilapidated," then he was to classify it as "sound" or "deteriorating." The use of this technique in 1960 was designed to maintain comparability with the 1950 enumeration of condition, when only the two categories, not dilapidated and dilapidated, were reported. The change to the three-way classification of condition in 1960 reflects the growing interest in housing quality and its importance in slum clearance and urban renewal programs.

The new classification and improved training techniques, designed to yield more adequate measures of potential urban blight, were developed by a group of experts working with the census staff. Field studies were conducted to explore the feasibility of the three-way classification and to test various types of training instructions that would define and convey to enumerators the concepts of the three levels of condition. While the 1950 concept and definition of the category "dilapidated" were retained without change for 1960, additional study was required to develop the concepts and terminology for the two other categories.

Although detailed oral and written instructions and visual aids were provided, it was not possible to achieve uniform results in applying the criteria for determining the condition of a unit. Data on condition for small areas, which depend on the work of only a few enumerators, may have a wider margin of relative error than data for larger areas, which are based on the work of a number of enumerators.

The 1960 category "dilapidated" is considered comparable with the 1950 category "dilapidated," since the basic 1950 concept of dilapidation was retained in 1960. The 1960 categories "sound" and "deteriorating" combined are comparable with the 1950 category "not dilapidated." It is possible, however, that the change in categories introduced an element of difference between the 1960 and 1950 statistics.

The concept of "dilapidation" replaced the concept of "needing major repairs" which was used in the 1940 Census. Because the two terms differ significantly, the 1940 results are not comparable with the 1950 or 1960 results on condition.

Water supply (H9). --A housing unit is classified in the tables as having "piped water inside structure" if there is running water inside the structure and it is available to the occupants of the unit. A unit has piped hot water even though the hot water is not supplied continuously; for example, it may be supplied only at certain times of the day, week, or year. Units with "piped water outside structure" have no running water inside the structure but have running water available on the same property, either outdoors or in another structure. In the category "no piped water" are units for which the only source of water is a hand pump, open well, spring, cistern, etc., and units in which the occupants obtain water from a source which is not on the same property.

The 1950 Census data on water supply are comparable with the 1960 data. The 1940 Census data, however, were presented on the basis of the availability of piped water inside or outside the unit rather than inside or outside the structure. The 1960 count of units with piped water inside structure may be considered comparable with the 1940 count of units with running water in the unit, except where there is an appreciable number of units with running water inside the structure but outside the unit.

Toilet facilities (H10). --A housing unit has a flush toilet if it is inside the structure and available for the use of the Occupants of the unit. Flush toilets for exclusive use are differentiated from those that are shared with occupants of other units. Units with other toilet facilities, such as privy, chemical toilet, or outside flush toilet, and units with no

facilities or none" (reported "none" or "no flush toilet for the use of this household" on the enumeration forms).

Data comparable with the 1960 data were provided by both the 1950 and 1940 Censuses.

Bathing facilities (H11).-- A housing unit has a bathtub or shower if either facility, supplied with piped water (not necessarily hot water), is inside the structure and available for the use of the occupants of the unit. Bathing facilities for exclusive use are differentiated from those that are shared with occupants of other units. The category "none" consists of units with only portable facilities, as well as units having no bathing facilities inside the structure and available for the use of the occupants.

Data comparable with the 1960 data were provided by both the 1950 and 1940 Censuses.

Exclusive or shared use. --Facilities are "for exclusive use" if they are used only by the occupants of the one housing unit, including lodgers or other unrelated persons living in the housing unit.

Facilities are "shared" if they are used by occupants of two or more housing units, or if they would be shared with the occupants of a unit now vacant. Shared facilities may be inside one of the units in the structure or may be centrally located where they can be reached by occupants of all units that share them.

Inside or outside structure. --Facilities are located “inside the structure" if they are located inside the same structure as the housing unit. They may be located within the housing unit itself, or they may be located in a hallway or in a room used by occupants of several units. It may even be necessary to go outdoors to reach that part of the structure in which the facilities are located. Facilities in the basement, on an enclosed porch, or enclosed by partitions on an otherwise open porch, are “inside the structure." Facilities on an open porch (for example, piped water) are "outside the structure.'

Bathroom (H30).-A housing unit has a complete bathroom if it has a flush toilet and bathtub (or shower) for the exclusive use of the occupants of the unit and also has piped hot water. (The requirement that the unit must have hot water was imposed during the processing of the data in an edit combining the items on bathrooms and hot water.) The facilities must be located inside the structure but need not be in the same room. A partial bathroom consists of toilet or bathing facilities for exclusive use, but not both. Units with a partial bathroom in addition to a complete bathroom are published in the category "1 plus partial" in some tables and "more than 1" in other tables. Units with only a partial bathroom are included in the published category "shared or none" together with units which share or lack bathroom facilities.

No data on number of bathrooms were provided in the 1950 or 1940 Censuses; however, data were presented on the number of units with both private flush toilet and bathtub (or shower).

Source of water (H31).- The source of water was to be reported in one of three categories. "Public system or private company" refers to a common source supplying running water to more than five houses. The source may be a city or county water department, a water district, a private water company, or a cooperative or partnership group. "Individual well" describes a source which serves five or fewer houses from a well on the property of the unit being enumerated or on a neighboring property. The water from such a well may be hand drawn, wind drawn, or power drawn. It may be piped or not piped; or it may be stored in tanks