American Community Survey
What's special about the American Community Survey?
The decennial census is taken only every 10 years. In the 2010 Census, there were only eight questions on the questionnaire, but the survey is intended to reach everyone in the country. The questions involve only number and relationship of people in each household, race, ethnicity, and type of housing unit.
The American Community Survey is an ongoing survey conducted by the U.S. Bureau of the Census. It includes a great many more questions than the decennial census, but gets responses from only about 1% of all households each year (less than 1,000 per year in Alexandria). Statistics include income, housing costs, wages, journey to work and travel mode, health insurance, and many other characteristics that are not covered in the decennial census.
Because this survey is given to such a small sample of the total population each year, year-to-year differences in these estimates often result from differences in the characteristics of the sample selected from the total population, and may or may not indicate trends in the total population.
Three-year and five-year averages of this data represent more responses and are reported for smaller areas and populations. Five-year averages are reported to the Census Tract and Block Group level, and are intended to replace the census "long form" that was completed by a sample of households in the 2000 and prior decennial censuses.
Large Margin of Error Possible in Estimates - use small numbers with caution
In using the American Community Survey data, it is important to remember that both the annual survey estimates and the long-term averages are based on a very small sample, on the order of 1% of households and population in the City each year. A population of 100 or 200 with a given characteristic reported in the survey results thus is based on one to two people from the sample reporting that characteristic each year. Control totals for the City in these estimates are based on Census Bureau estimates based on vital statistics (reported births and deaths) and internal migration estimates controlled to the most recent decennial census, not an actual count of the population currently living in the City. Census tract and block group statistics from the American Community Survey 5-year averages in particular are based on very small numbers of respondents.
Current American Community Survey Data for Alexandria
- American Community Survey 2013 Narrative Summary. This brief newsletter prepared by city staff reports highlights from the 2013 annual data, released by the Census Bureau on September 18, 2014. The data shows an increase in the share of Alexandria’s households that are families with children, and a continuing trend to increasing ethnic and racial diversity. The senior share of the population continues to decline, but that trend is expected to reverse soon as more and more baby boomers pass the 65-year mark (October 2, 2014).
- County-to-county commuter flows. These graphs show the percent of commuters into and out of Alexandria from the top 25 county origins and destinations based on the American Community Survey 2006-2010 average, and compare these flows to those from the same jurisdictions in 2000. There were some subtle but no significant changes among the major origins and destinations over this relatively short period (March 9, 2013).
- American Community Survey 2011 Narrative Summary. This brief report prepared by city staff summarizes information about Alexandria from the 2011 1-year survey. The report notes changes since the 2010 Census, and compares Alexandria to nearby jurisdictions, other counties and independent cities of 65,000 people or more in the U.S., places in the U.S. of 65,000 people or more, and the United States as a whole (January 29, 2013).
- County-to-county migration patterns data, based on the 2005-2009 American Community Survey 5-year average, was released by the Census Bureau for the first time since the 2000 Census. Links to graphs showing the top 100 places for migration into and out of Alexandria are provided below under Past American Community Survey data ( March 29, 2012).
- Alexandria 2010 Census Data Profile. A profile of the city in 2010 prepared by city staff based on a variety of U.S. Census sources is now available for on-line viewing or downloading. Based on the 2010 U.S. Census, 2006-2010 American Community Survey 5-year average data by census tract, and the 2010 American Community Survey, the report includes comparisons to the City in 2000 and earlier, to surrounding areas including the Washington, D.C. metropolitan area, and to the U.S as a whole. Data on population and race dating from the first U.S. Census in 1790 is included. The report outlines the important and continuing influence of the postwar baby boom on growth and change in the U.S. and the city. Recent changes in race and ethnicity within the city are mapped. The report also includes data on income, education, housing tenancy, ancestry, commuting, disability, foreign-born population, geographic mobility, and many other characteristics that help define the Alexandria of today (March 5, 2012).
2010 American Community Survey Summary Table . This table was prepared by City staff to compare some key statistics for 2010 and prior years. The table compares various statistics for 2010 with 2009, the 2005-2009 American Community Survey 5-year average, and the 2000 Census. In making comparisons, users should consider that the American Community Survey is based on a very small sample (less than 1000 households in the City each year), and some changes in values, particularly where the values are small, do not necessarily indicate a change in this value for the entire population.
Some of the changes (and non-changes) to note in this table include the following:
- The over-65 population remains a relatively constant share of the City’s population in spite of a significant national increase in the percentage over 65.
- Disability seems to be decreasing, though disability affects a much larger share of people as they reach age 65.
- Household size and percent single-person households are essentially unchanged since 2000.
- Labor force participation of the 16-and-over population in Alexandria has increased significantly in 10 years, perhaps as those not in the labor force seek less expensive housing.
- Unemployment is low among residents, but up since 2000 as one would expect. Unemployment is slightly (within the margin of error) down from 2009.
- Commuting share by single-occupant vehicle is significantly declining, and is now less than 60% of workers living in Alexandria.
- The share of people commuting by transit is up 28.7% since 2000, reaching 21.1% of all workers living in the City in 2010.
- Median household income has fallen since 2007.
- The poverty rate has remained approximately constant (within the margin of error of the data) since 2000.
- Educational attainment of the City’s population is substantially increasing.
- There was a dramatic increase in the percentage of households who had lived in the same house for at least one year in 2010 compared to 2009 and to the 2005-2009 average. Only 14.3% of households were in a new location over the prior year in 2010, compared to 23.4% in 2009. This likely in part reflects increasing difficulty in selling houses. However, because more than half the City's households are renters, it also may reflect a tight rental market, making it harder for both renters and owners to move. Difficulty in finding new jobs and uncertainty in the job market also make peope less willing to relocate.
Past American Community Survey Data
The City recommends that users not rely on the absolute numbers from the 2009 American Community Survey annual or 5-year average reports, but instead emphasize percentage shares of population and households when using these estimates. The 2010 Census shows an estimate of 139,966 for the total population of Alexandria on April 1, 2010, compared to 150,006 for the 2009 American Community Survey estimate for July 1, 2009. The 2009 estimate is 7.2% more than the 2010 population estimate from the more complete Census survey in 2010. There was no decline in population between 2009 and 2010 in the city; this difference is an error in the 2009 estimate.
- 2009 American Community Survey 5-year Average Data for Alexandria . (PDF file) A City-prepared table of selected population, economic and housing statistics from 2009 American Community Survey 5-year average data, compared to Census 2000 and 2009 annual data.
- County-to-county migration inflows
to Alexandria, 11 x 17 inch PDF graph showing the top 100 world sources of people moving to Alexandria from the American Community Survey 2005-2009 5-year average data.
County-to-county migration outflows from Alexandria, 11 x 17 inch PDF graph showing the top 100 destinations in the U.S. for people moving from Alexandria.
To magnify these graphs for readability, save to your computer and open in Acrobat Reader, or use the + symbol on the gray navigation band at bottom center of the document window. You may need to move your cursor to the document window to see this navigation band.
These two graphs are based on Census tables from a sample of about 1% of all households per year, for a total of about 5%, so small numbers are very indefinite in ordering and have a margin of error much larger than the number itself. The lower rankings in the top 100 and below are based on responses from just a few to 1 or 2 households, and locations may range widely from year to year.
The total for moves in for this sample was 22,509. By percentage of the total, the top four origins were 16.5% from Fairfax County, 11.1% from Arlington County, 7.3% from Washington, D.C., then a big drop to 2.9% from Africa.
The total for moves out was 19,022. By percentage, the top four destinations were 27.5% to Fairfax County, 9% to Arlington County, 6.9% to Prince William County, and 4.7% to Washington, DC.
The data is based on responses to the question asking the place of residence one year ago for anyone in a household one year old or older. This could be two or three moves ago for some people – it’s not necessarily where they came from just before moving here (or there).
For a further discussion of the data used to prepare these statistics, and to download the entire data set, please visit the U.S. Census web page for the data at the link below:
- U.S. Census Bureau County-to-County Migration Information Page
- Census 2000 Tract Map for use with American Community Survey census tract level data prior to 2010.
American Community Survey data and further information from the Bureau of the Census
- American Community Survey Handbook for General Data Users This handbook from the Census Bureau provides information about the American Community Survey and how to obtain and make use of data from the survey.
- American Community Survey - Census Main Page This link provides access to the Census Bureau's main page for the American Community Survey annual and average data. Follow the link at the top of the page to 2011 for detailed information from American Factfinder for the 2011 American Community Survey 1-year estimates.
To see only data for Alexandria, choose Alexandria city, Virginia as your geography, click Add to add to your selections, close the geography window, and scan through the hundreds of tables and cross-tabulations that are available just for Alexandria from this rich data source.
For further information, assistance with navigating the Census web site, or getting other Census statistics and maps for the City of Alexandria, please contact Mary Catherine Collins, Urban Planner, at 703.746.3832.