Census Geography
Census Geography is a collective term referring to the types of geographic areas used by the Census Bureau in its data collection and tabulation operations. This diagram shows the many geographic types for which data are available from the U.S. Census Bureau. With connecting lines, the diagram shows the hierarchical relationships between geographic types.
Geographic Terms
Census tract
A small, relatively permanent statistical subdivision of a county delineated by a local committee of census data users for the purpose of presenting data. Census tract boundaries normally follow visible features, but may follow governmental unit boundaries and other non-visible features in some instances; they always nest within counties. Designed to be relatively homogeneous units with respect to population characteristics, economic status, and living conditions at the time of establishment, census tracts average about 4,000 inhabitants. They may be split by any sub-county geographic entity.
Census tract number
Used to uniquely identify a census tract within a county. (More ...)
Place
The Census Bureau uses this term to refer to most cities, some towns, villages and boroughs.
Consult Glossary for more definitions.
Summary Files
Summary File (SF)
Statistics for a large number of geographic areas that are designed to show great subject matter detail presented in tabular form.From the data collected in the 2010 Census, there were two main summary files produced. See the individual definitions for Summary Files 1 and 2. From the data collected in Census 2000, there were four main summary files produced. See the individual definitions for Summary Files 1, 2, 3, and 4 for a more in-depth explanation of each. In the 1990 and 1980 censuses, the files were referred to as Summary Tape Files (STFs).
SF1 (Summary File 1)
Data files available from Census 2000 and the 2010 Census. This file presents 100-percent population and housing figures for the total population, for 63 race categories, and for many other race and Hispanic or Latino categories. This includes age, sex, households, household relationship, housing units, occupancy status, and tenure (whether the residence is owned or rented). Also included are selected characteristics for a limited number of race and Hispanic or Latino categories. Data are available down to the block level for many tabulations, but only to the census-tract level for others.
SF2 (Summary File 2)
Summary File 2 presents data similar to the information included in Summary File 1. For the 2010 Census, the data are shown down to the census tract level for up to 331 race, Hispanic or Latino, and American Indian and Alaska Native groups. For Census 2000, these data are shown down to the census tract level for up to 250 race, Hispanic or Latino, and American Indian and Alaska Native tribe categories. For data to be shown in SF 2, a population category must meet a population size threshold of 100 or more people of that specific population category in a specific geographic area.
SF3 (Summary File 3)
This is a 1-in-6 sample of the population, down to the Census Block Group level (less resolution than SF1 and SF2). It presents detailed population and housing data (such as place of birth, education, employment status, income, value of housing unit).
SF4 (Summary File 4)
This is a 1-in 6 sample of the population, down to the Census tract level (less resolution than SF1, SF2 and SF3). It has the same information as SF3, but is organized by race or tribe.