Social Work 509-- Essentials of Community and Organizational Practice

The Decennial Census:

The decennial census is a constitutionally mandated count of the population of the U.S. which is conducted by the government every ten years. The count is used for apportioning Congressional seats, as well as many other purposes, such as demographic research, allocating funding, and informing public policy.

Historical Changes:

The Census has changed greatly over time. Though the first Census in 1790 did little more than count population, over the years it has grown to include many other types of information. Many questions and terminology (e.g. racial categories) have changed over time as well.

The Long Form and the American Community Survey:

Over time Congress became concerned that there were too many questions. In 1940 the Long Form was created as a way of finding out more detailed information (e.g. questions on income and educational attainment) from a sample of the population. The long form of the Census was sent to 1 in 6 households. The 2000 Census was the last time the long form was used. Since 2000, the American Community Survey has replaced the long form. The American Community Survey is an ongoing survey of a sample population that will provide us with detailed and more current information.

Understanding Census geography is not always as simple as it would seem. there are traditional methods for dividing up geography in the United States that most people are familiar with, such as states, counties, and zip codes. The Census uses its own methods and terminology for geography as well, the most prominent of which is a division known as a "Census tract," which divides up counties. The links on this page are provided to help users comprehend Census geography and how it can be used to better understand population and demographic data.

The following image offers a basic outline of Census geographic divisions. For a full explanation of the diagram, see the Hierarchy Diagrams page on the Census Bureau website