U.S. Department of Commerce

Economics and Statistics Administration

U.S. CENSUS BUREAU

census.gov

Physical Characteristics of Housing: 

2009–2011

American Community Survey Briefs

By Christopher Mazur 

Issued April 2013

ACSBR/11-20

INTRODUCTION

This report presents data on basic physical and structural characteristics of the total housing inventory 

at the national level and for metropolitan statistical 

areas (metro areas) based on the 2009–2011 American 

Community Survey (ACS) 3-year estimates.1 The report 

will examine types of housing structures, newer and 

older houses, and the size of the houses measured by 

the number of rooms.

STRUCTURE TYPE

According to the 2009–2011 ACS, 131.8 million 

housing units were located in the United States. Of 

these housing units, 81.1 million (61.5 percent) were 

single-family houses not attached to any other structure (referred to as “detached, single-family houses”). 

Another 7.6 million (5.8 percent) were classified as single-family houses attached to one or more other structures, commonly referred to as “townhouses” or “row 

houses.” Buildings with 2 to 4 apartments composed 

10.9 million (8.3 percent) housing units of the inventory, while 12.3 million (9.3 percent) housing units 

were located in buildings with 5 to 19 apartments. 

Large buildings with at least 20 apartments accounted 

for 11.2 million (8.5 percent) housing units. There 

were 8.6 million (6.5 percent) mobile homes, while the 

remaining 111,000 (0.1 percent) housing units in the 

inventory were classified as “other,” which includes 

occupied boats, recreational vehicles, and vans.

1 For more information on metro areas, please see 

<www.census.gov/population/metro/>.

The vast majority of metro areas, 349 of the 366, contained mainly detached, single-family houses. Among 

the 17 metro areas that did not, New York-Northern 

New Jersey-Long Island, NY-NJ-PA, had the lowest 

percentage of detached, single-family houses with 

36.3 percent. Naples-Marco Island, FL (40.0 percent), 

had the second lowest percentage, while Miami-Fort 

Lauderdale-Pompano Beach, FL, followed with 42.3 

percent of its housing inventory classified as detached, 

single-family houses. 

In five metro areas, townhouses or row houses 

composed more than 20.0 percent of the housing 

inventory. These metro areas were PhiladelphiaCamden-Wilmington, PA-NJ-DE-MD (29.1 percent); 

Baltimore-Towson, MD (28.8 percent); Reading, PA 

(23.4 percent); Trenton-Ewing, NJ (20.9 percent); and 

Allentown-Bethlehem-Easton, PA-NJ (20.8 percent). 

Though not statistically different from one another, 

New York-Northern New Jersey-Long Island, NY-NJ-PA 

(26.8 percent), and Miami-Fort Lauderdale-Pompano 

Beach, FL (26.6 percent), were the only metro areas 

that had greater than 25.0 percent of the housing 

inventory located in large buildings with at least 20 

apartments.2 Following these two metro areas, the 

largest percentage of housing inventory located within 

large apartment buildings were found in Honolulu, HI 

(24.5 percent); Fargo, ND-MN (20.2 percent); NaplesMarco Island, FL (18.2 percent); and Los Angeles-Long 

Beach-Santa Ana, CA (17.1 percent). 

2 All comparisons made in this report have undergone statistical 

testing and are significant at the 90.0 percent confidence level unless 

otherwise noted.
2 U.S. Census Bureau Source: U.S. Census Bureau, 2009–2011 American Community Survey. 0 500Miles 0 100 Miles 0 100 Miles Percent15.0–19.9 10.0–14.9 5.0–9.9 Note: Metropolitan Statistical Areas defined by the Office of Management and Budget as of December 2009. 20.0 or more Fi Mobile Homes as a Percentage of All Housing Units by Metropolitan Statistical Area: 2009–2011 gure 1. U.S. percent is 6.5 Less than 5.0
U.S. Census Bureau 

3

Source: U.S. Census Bureau, 2009–2011 American Community Survey.

0 500Miles

0 100 Miles

0 100 Miles

Percent

7.5–9.95.0–7.42.5–4.9

Note: Metropolitan Statistical Areas defined 

by the Office of Management and Budget as of December 2009.

10.0 or more

Fi

Newer Houses as a Percentage of All Housing Unitsby Metropolitan Statistical Area: 2009–2011

gure 2.

U.S. percent is 6.0

Less than 2.5
4 U.S. Census Bureau

Mobile homes composed more than 

20.0 percent of the housing inventory in 11 metro areas. The largest 

percentage of mobile homes as part 

of a metro area’s housing inventory 

was in Farmington, NM, with 32.0 

percent, followed by Yuma, AZ, 

with 29.0 percent. Besides these 

two metro areas, Lake Havasu CityKingman, AZ (26.7 percent), was 

the only other metro area to have 

mobile homes account for more 

than 25.0 percent of its housing 

inventory (Figure 1).

NEWER/OLDER HOUSES

For the purpose of this report, newer 

houses are defined as those built in 

the year 2005 or later, while older 

houses are those built before the 

year 1950. In the United States, estimates from the 2009–2011 ACS data 

show that 6.0 percent of all housing units were newer houses, while 

older houses accounted for 19.3 percent of the total housing inventory.

The percentage of newer houses 

within a metro area’s housing 

inventory ranged from 1.2 percent 

in Pittsfield, MA, and Elmira, NY, to 

16.4 percent in Gulfport-Biloxi, MS 

(Figure 2). The housing inventory of 

172 metro areas had a significantly 

higher percentage of newer houses 

than the national percentage of 6.0 

percent, while 142 metro areas had 

a significantly lower percentage 

than the national percentage. Fiftytwo metro areas were not statistically different from the national 

percentage.

Newer houses accounted for more 

than 10.0 percent of the housing inventory in 39 metro areas. 

Gulfport-Biloxi, MS (16.4 percent) 

was the only metro area with more 

than 15.0 percent of its housing 

inventory built in 2005 or later.

The range for older houses as a 

percentage of a metro area’s housing inventory was 0.5 percent in 

Naples-Marco Island, FL, to 49.5 

percent in Elmira, NY. The percentage of older houses in the housing inventory of 127 metro areas 

was significantly higher than the 

national percentage of 19.3 percent, while 217 metro areas had a 

significantly lower percentage than 

the national percentage. Twentytwo metro areas were not statistically different from the national 

percentage.

In 30 metro areas, older houses 

accounted for more than one-third 

of the housing inventory, while in 

11 metro areas older houses were 

greater than 40.0 percent. Of these 

11 metro areas, homes built before 

1950 exceeded 45.0 percent of the 

housing inventory in Elmira, NY 

(49.5 percent), Scranton–WilkesBarre, PA (48.8 percent), Johnstown, 

PA (47.0 percent), and Pittsfield, MA 

(46.9 percent).

ROOMS

The 2009–2011 ACS data estimate 

that the median number of rooms 

within a housing unit in the United 

States is 5.5.

Of all 366 metro areas, the median 

number of rooms ranged from 4.7 

in 5 metro areas (Yuma, AZ; MiamiFort Lauderdale-Pompano Beach, FL; 

Los Angeles-Long Beach-Santa Ana, 

CA; Honolulu, HI; and Fairbanks, 

AK) to 6.8 in Provo-Orem, UT. 

Sixteen metro areas had a median 

number of rooms that was larger 

than 6.0. Of these 16 metro areas, 

Provo-Orem, UT, had the largest percentage (30.6 percent) of its housing units having 9 or more rooms. 

Other metro areas with a high percentage of its housing units having 

9 or more rooms were Logan, UT-ID 

(26.6 percent); Idaho Falls, ID (26.5 

percent); and Ogden-Clearfield, UT 

(24.8 percent). Along with these 

metro areas, Washington-ArlingtonAlexandria, DC-VA-MD-WV (22.3 

percent); Rochester, MN (21.8 

percent); and Salt Lake City, UT 

(21.0 percent) were the only other 

metro areas with greater than 20.0 

percent of its housing units having 

9 or more rooms.

Ten metro areas had a median number of rooms below 5.0. Manhattan, 

KS (11.7 percent), and Myrtle 

Beach-North Myrtle Beach-Conway, 

SC (11.6 percent), had the largest 

percentage of its housing units 

having just one room and were the 

only metro areas to have greater 

than 10.0 percent of its housing 

units composed of one room. The 

metro areas with the next largest 

percentage of housing units with 

one room were Farmington, NM 

(6.5 percent), and Flagstaff, AZ (6.1 

What Is the American Community Survey?

The American Community Survey (ACS) is a nationwide survey designed 

to provide communities with reliable and timely demographic, social, 

economic, and housing data for the nation, states, congressional districts, counties, places, and other localities every year. It has an annual 

sample size of about 3.3 million addresses across the United States and 

Puerto Rico and includes both housing units and group quarters (e.g., 

nursing facilities and prisons). The ACS is conducted in every county 

throughout the nation, and every municipio in Puerto Rico, where it 

is called the Puerto Rico Community Survey. Beginning in 2006, ACS 

data for 2005 were released for geographic areas with populations of 

65,000 and greater. For information on the ACS sample design and 

other topics, visit <www.census.gov/acs/www>.
U.S. Census Bureau 5

percent), which were not statistically different from one another.

SOURCE AND ACCURACY 

The data presented in this report 

are based on the ACS sample 

interviewed in 2009 through 2011. 

The estimates based on this sample 

approximate the actual values and 

represent the entire household 

and group quarters population. 

Sampling error is the difference 

between an estimate based on 

a sample and the corresponding 

value that would be obtained if 

the estimate were based on the 

entire population (as from a census). Measures of the sampling 

errors are provided in the form of 

margins of error for all estimates 

included in this report. All comparative statements in this report 

have undergone statistical testing, 

and comparisons are significant 

at the 90 percent level unless 

otherwise noted. In addition to 

sampling error, nonsampling error 

may be introduced during any of 

the operations used to collect and 

process survey data such as editing, reviewing, or keying data from 

questionnaires. For more information on sampling and estimation 

methods, confidentiality protection, 

and sampling and nonsampling 

errors, please see the 2011 ACS 

Accuracy of the Data document 

located at <www.census.gov

/acs/www/Downloads/data

_documentation/Accuracy/ACS

_Accuracy_of_Data_2011.pdf>.
6 U.S. Census Bureau

Appendix Table A.

Physical Characteristics of Total Housing Inventory by Metropolitan Statistical 

Area1: 2009–2011

(For information on confidentiality protection, sampling error, nonsampling error, and definitions, see www.census.gov/acs/www)

Area

Total housing units

Percentage 

detached, 

single-family 

houses

Median year 

structure built

Median number 

of rooms

Estimate

Margin 

of 

error2

(±) Percent 

Margin 

of

 error2 

(±) Estimate

Margin 

of 

error2 

(±) Estimate

Margin 

of 

error2 

(±)

 United States . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131,826,591 3,846 61.5 0.1 1975 1 5.5 0.1

Atlanta-Sandy Springs-Marietta, GA . . . . . . . . . . . . . . . . . . 2,166,002 1,092 67.0 0.3 1989 1 6.0 0.1

Austin-Round Rock-San Marcos, TX . . . . . . . . . . . . . . . . . . 709,474 979 59.1 0.4 1990 1 5.3 0.1

Baltimore-Towson, MD . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1,133,447 1,095 45.3 0.3 1971 1 6.2 0.1

Birmingham-Hoover, AL . . . . . . . . . . . . . . . . . . . . . . . . . . . 500,064 819 69.3 0.5 1979 2 5.8 0.1

Boston-Cambridge-Quincy, MA-NH . . . . . . . . . . . . . . . . . . . 1,884,815 1,191 47.8 0.3 1957 1 5.5 0.1

Buffalo-Niagara Falls, NY . . . . . . . . . . . . . . . . . . . . . . . . . . 519,018 870 59.1 0.5 1954 1 5.8 0.1

Charlotte-Gastonia-Rock Hill, NC-SC . . . . . . . . . . . . . . . . . 738,811 710 67.0 0.4 1989 1 5.6 0.1

Chicago-Joliet-Naperville, IL-IN-WI . . . . . . . . . . . . . . . . . . . 3,797,596 1,373 51.9 0.2 1966 1 5.5 0.1

Cincinnati-Middletown, OH-KY-IN . . . . . . . . . . . . . . . . . . . . 917,554 870 65.0 0.4 1971 1 5.8 0.1

Cleveland-Elyria-Mentor, OH . . . . . . . . . . . . . . . . . . . . . . . . 956,106 877 65.0 0.3 1959 1 5.9 0.1

Columbus, OH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 793,224 818 61.6 0.4 1976 1 5.7 0.1

Dallas-Fort Worth-Arlington, TX . . . . . . . . . . . . . . . . . . . . . . 2,508,595 1,298 63.6 0.2 1985 1 5.5 0.1

Denver-Aurora-Broomfield, CO . . . . . . . . . . . . . . . . . . . . . . 1,079,841 781 59.3 0.3 1980 1 5.8 0.2

Detroit-Warren-Livonia, MI . . . . . . . . . . . . . . . . . . . . . . . . . . 1,885,676 742 69.9 0.3 1964 1 5.8 0.1

Hartford-West Hartford-East Hartford, CT . . . . . . . . . . . . . . 507,490 871 59.6 0.5 1964 2 5.7 0.1

Houston-Sugar Land-Baytown, TX . . . . . . . . . . . . . . . . . . . 2,315,153 950 62.1 0.3 1984 1 5.4 0.1

Indianapolis-Carmel, IN . . . . . . . . . . . . . . . . . . . . . . . . . . . . 758,339 613 68.4 0.4 1977 1 5.8 0.1

Jacksonville, FL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 599,167 924 62.4 0.6 1986 1 5.6 0.1

Kansas City, MO-KS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 883,811 673 69.9 0.3 1975 1 5.9 0.1

Las Vegas-Paradise, NV . . . . . . . . . . . . . . . . . . . . . . . . . . . 841,950 435 58.0 0.5 1995 1 5.2 0.1

Los Angeles-Long Beach-Santa Ana, CA . . . . . . . . . . . . . . 4,495,216 1,583 49.8 0.2 1966 1 4.7 0.1

Louisville/Jefferson County, KY-IN . . . . . . . . . . . . . . . . . . . . 560,298 612 69.5 0.5 1973 1 5.5 0.2

Memphis, TN-MS-AR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 551,323 644 68.8 0.5 1979 1 5.7 0.1

Miami-Fort Lauderdale-Pompano Beach, FL............. 2,465,506 1,142 42.3 0.2 1979 1 4.7 0.1

Milwaukee-Waukesha-West Allis, WI . . . . . . . . . . . . . . . . . . 670,319 630 54.5 0.4 1962 1 5.4 0.1

Minneapolis-St. Paul-Bloomington, MN-WI . . . . . . . . . . . . . 1,355,786 1,089 60.7 0.3 1977 1 6.1 0.1

Nashville-Davidson—Murfreesboro—Franklin, TN . . . . . . . 668,800 906 65.4 0.5 1984 1 5.7 0.1

New Orleans-Metairie-Kenner, LA . . . . . . . . . . . . . . . . . . . . 539,478 644 60.8 0.5 1973 1 5.4 0.1

New York-Northern New Jersey-Long Island, NY-NJ-PA . . . 7,530,183 2,109 36.3 0.1 1956 2 4.8 0.1

Oklahoma City, OK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 540,003 613 71.9 0.5 1977 1 5.4 0.1

Orlando-Kissimmee-Sanford, FL . . . . . . . . . . . . . . . . . . . . . 943,949 1,119 59.6 0.4 1989 1 5.4 0.1

Philadelphia-Camden-Wilmington, PA-NJ-DE-MD . . . . . . . 2,435,028 1,488 44.6 0.2 1962 1 6.1 0.1

Phoenix-Mesa-Glendale, AZ . . . . . . . . . . . . . . . . . . . . . . . . 1,801,538 857 64.2 0.3 1989 1 5.4 0.1

Pittsburgh, PA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1,101,964 1,325 67.1 0.3 1957 1 5.9 0.1

Portland-Vancouver-Hillsboro, OR-WA . . . . . . . . . . . . . . . . 926,114 716 61.9 0.3 1978 1 5.5 0.1

Providence-New Bedford-Fall River, RI-MA . . . . . . . . . . . . . 694,298 524 53.9 0.5 1957 1 5.4 0.1

Raleigh-Cary, NC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 467,429 573 63.2 0.6 1992 2 5.8 0.1

Richmond, VA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 532,432 1,098 70.7 0.5 1979 1 6.0 0.1

Riverside-San Bernardino-Ontario, CA . . . . . . . . . . . . . . . . 1,502,164 1,112 69.0 0.3 1984 1 5.4 0.1

Sacramento—Arden-Arcade—Roseville, CA . . . . . . . . . . . 872,477 1,059 67.6 0.5 1980 1 5.4 0.1

St. Louis, MO-IL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1,236,978 961 69.2 0.3 1970 1 5.6 0.1

Salt Lake City, UT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 411,267 375 64.6 0.5 1979 1 6.1 0.2

San Antonio-New Braunfels, TX . . . . . . . . . . . . . . . . . . . . . 840,750 754 68.1 0.4 1983 1 5.4 0.1

San Diego-Carlsbad-San Marcos, CA . . . . . . . . . . . . . . . . . 1,165,610 1,081 51.4 0.3 1977 1 5.1 0.1

San Francisco-Oakland-Fremont, CA . . . . . . . . . . . . . . . . . 1,743,042 1,167 49.5 0.3 1964 1 5.0 0.1

San Jose-Sunnyvale-Santa Clara, CA . . . . . . . . . . . . . . . . . 650,066 558 54.3 0.5 1973 2 5.2 0.1

Seattle-Tacoma-Bellevue, WA . . . . . . . . . . . . . . . . . . . . . . . 1,464,902 982 59.4 0.3 1979 1 5.5 0.1

Tampa-St. Petersburg-Clearwater, FL . . . . . . . . . . . . . . . . . 1,354,587 1,023 55.5 0.3 1982 2 5.1 0.1

Virginia Beach-Norfolk-Newport News, VA-NC . . . . . . . . . . 687,066 1,144 61.6 0.4 1978 1 5.9 0.1

Washington-Arlington-Alexandria, DC-VA-MD-WV . . . . . . . 2,217,179 1,296 46.5 0.2 1978 1 6.1 0.1

– Represents or rounds to zero. 1

 Fifty most populous metropolitan statistical areas based on the 2010 Census. Metropolitan statistical areas defined by the Office of Management and Budget 

as of December 2009. 2

 Data are based on a sample and are subject to sampling variability. A margin of error is a measure of an estimate’s variability. The larger the margin of error 

is in relation to the size of the estimate, the less reliable the estimate. When added to and subtracted from the estimate, the margin of error forms the 90 percent 

confidence interval.

Source: U.S. Census Bureau, 2009–2011 American Community Survey.