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Community & Urban Research: Census & Demographic Data

1. Finding and Using Census Data

Held every 10 years since 1790, the Census is the most comprehensive demographic survey in the United States. Although the questions asked change from year to year, through 2000 there were always variables related to age, race and ethnicity, languages spoken, education, ancestry, income, home ownership versus renting, and more. In theory, the Census counts every person living in the United States.  While there are be portions of the population that go uncounted, it is still the closest we have to complete demographic and economic data on the U.S. population.

The Census Bureau's American FactFinder gives full access to the 2010 census, the 2000 census and partial access to the 1990 census. When comparing Census data from different years, remember that demographic definitions and other information are reported differently for each census. A variable reported in 1950 may not be available in 2000 and vice-versa.

Here is a detailed view of the data available in American FactFinder.

2. Defining your community

When researching communities we must determine how Census areas overlay with the streets and neighborhoods we know from everyday life. Neighborhoods are not official Census boundaries. 

To do so determine what Census tracts best match up with your community to find the Census data you need. Tract boundaries may not match up exactly with the official New York City boundaries of your community, so you will also need to determine if you will include portions (blocks, block groups) of tracts that are not fully included in your neighborhood. If so, you'll need to use a combination of street maps, Census tract maps and block maps to define the specific area of research.

Be aware also that Census tract numbers and boundaries may change over time. For a detailed view of Census tract, block group & block information, consult the Census Bureau's Reference Maps or the mapping applications in American FactFinder by selecting Geographies, or use the New York City Department of Planning's NYC Population FactFinder.

3. Find demographic data - American FactFinder

Here is a quick guide to finding Census tables on race and ethnicity for a geographic area of your choice.

Advanced Search provides two approaches to the selection of Population Groups. The best approach for you to use depends on the population groups you are interested in, and the kind of information you want to know about them.

  1. Basic Groups provides access to general information about basic race groups and ancestries, including population counts, household information, and employment data.
  2. Detailed Groups provides access to more population groups and more detailed information about those groups.

Search for Basic Groups

Start your search by clicking Race and Ethnic Groups. Then, select one of the entries listed on the Basic Groups tab. (You can select more than one group if you want.) AFF will add your choice to your search criteria, which are shown in the "Your Selections" box.

The data products available when you pick one of these entries will contain general information about your selected group (and possibly other groups). Click close on the Race and Ethnic Groups panel and view the tables.

Search for Detailed Groups

To search a more complete list of over 2,500 race and ethnic groups, tribes, ancestries, and countries of origin defined by the Census Bureau, use the Detailed Groups tab. Remember, after you add a group to your Selections you can limit your search to a Census tract or Block.

4. Census Geography

The Census uses both common geographies such as states, counties, places (cities), as well as geography very specific to the Census. Locally designated boundaries such as community planning areas, neighborhoods, police beats, library districts, etc. are largely ignored in favor of specialized Census geography which allows for a standardized way of looking at geographies smaller than a city. The key small areas are:

  • Blocks (Census Blocks) — This is the smallest unit of Census geography. Blocks (Census Blocks) are statistical areas bounded by visible features, such as streets, roads, streams, and railroad tracks, and by nonvisible boundaries, such as selected property lines and city, township, school district, and county limits and short line-of-sight extensions of streets and roads. Generally, census blocks are small in area; for example, a block in a city bounded on all sides by streets.
  • Block Groups (BGs) — A collection of blocks, a block group is the smallest geography for which sample data are tabulated. An Ideal block group has a population of 1,500 people, with populations ranging from 300 to 3000 people.
  • Census Tracts — Census tracts are small, relatively permanent statistical subdivisions of a county or county equivalent and generally have a population size between 1,200 and 8,000 people, with an optimum size of 4,000 people. The Census Bureau created census tracts to provide a stable set of boundaries for statistical comparison from census to census. Census tracts occasionally split due to population growth or merge when there is substantial population decline.

For more detailed information refer to the Census Geography Reference.

Census Questions

Questions change from Census to Census, sometimes dramatically, which means that the statistics available change from decade to decade. For most of the 20th Century, the Decennial Census has included a “short form” with questions answered by every household in the country, as well as a “long form” that is answered by about 1 in 6 households.

As of 2010, there is no longer a Census long form. A short form, containing only questions such as age, race and ethnicity, will be sent to every household in the country. A longer questionnaire called the American Community Survey (ACS) covers questions previously appearing on the decennial long form. Since 2005, the ACS - which includes approximately 50 questions - has been sent to 1 in 40 households in the U.S. Over a period of 5 years, this approximates the number of households that would have normally filled out a long form decennial Census. Starting in 2010, aggregates of 5 years of data will be released each year. This means that fresh demographic data about the country will be available every year instead of every 10 years. Although the ACS data is only sample data, it's a great improvement in the availability of recent demographic data. Note, ACS data are available in American FactFinder.

The easiest way to find out what information is available for a specific Census is to look at the Census questionnaires. If the question wasn’t asked, the information isn’t available.

The Census Bureau's Index of Questions webpage provides questions asked for decennial censuses from 1790-2010. For copies of the original Census questionnaires since 1790, see the Census publication Measuring the Census: The Decennial Censuses from 1790 to 2000.

Social Explorer (new)

  • Social Explorer - Explore demographic information, from census and economic data to election and religion data, and more. Users can visually explore change over time and understand the patterns behind the raw numbers.
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