Overview of Census Data
Data produced by the U.S. Census Bureau provides a wealth of information on the City of Alexandria and its residents. It is the primary source for the demographic studies, reports, and maps included on the demographics section of this website. Individuals can download their own custom data requests from the U.S. Census Bureau's website using
American Factfinder. Another popular resource on the U.S. Census Bureau's website is
Census Explorer, which provides basic information on populations through an interactive map.
The Census Bureau publishes data on their website https://www.census.gov/. Individuals can download their own custom data requests using American FactFinder. Instructions for using American FactFinder are below:
- Go to the "Quick Start" section in the center of the web page. Click in the entry box for "Geography" and enter Alexandria city, Virginia. The page will search for matching terms as you are typing, and when you see Alexandria city come up you can click on that entry if you wish to complete the entry.
- Click "GO" to the right of the data entry box. This will bring up a new page with check boxes for all the data items that are available for Alexandria. They appear to be provided in chronological order by when they are released, with the most recent at the top. At the time this was prepared, the DP-1 data set, Profile of General Population and Housing Characteristics 2010, was the top item in the list.
- Find DP-1 in the list, and click to turn on the check mark in the check box at DP-1.
- Click View or Download at the top or bottom of the list.
- If you click Download from this screen, your page will be downloaded as a Zip file in comma-delimited text format suitable for loading in data base applications including Excel.
- If you click View from this screen, you will have a choice of download options once the data appears, including Excel and PDF formats.
- After clicking View, if you wish to download, select the format you want and click OK. You will be given the choice of Opening or Saving the file.
- If you choose Open the file will open in a program appropriate to the format you selected. Once the file opens, you can save a copy to your desktop or another location of your choice.
- If you choose Save, the file will be saved in the default location where your downloads are saved, often in My Documents\Downloads
Once you have viewed or downloaded your data set, you can go back to the search page (click on the "Back to Search" in the upper left) and change the geography of your search, or change the search item.
- US Census Bureau Census 2000 home page
The 2000 Census provides the previous data based on a complete count of all households in the City. This data is available citywide as well as by geographic subareas smaller than the City as a whole, including blocks, block groups, and census tracts.
- City Census 2000 data maps for viewing or downloading (link to page with PDF file links).
- US Census Bureau American Community Survey home page
The American Community Survey annual statistics are citywide, and are based on surveys of a very small sample of the population each year. 5-year average statistics are now available from the period 2005 to 2009 by Census Tract and Block Group.
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.
The City recommends that users not rely on the absolute numbers from the 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.
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.
Census geographies are statistical subdivisions of a city or county. The City of Alexandria assists in the delineation of census tracts prior to each decennial census and ideally, the boundaries remain over a long period of time so that data can be easily compared between censuses. There are three geographies Tracts 2010 typically used for the presentation of census data. In descending order of size they are: tracts, block groups, and blocks.