Census Information
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Census Geography
- Census Bureau Geography Reference MapsVarious maps showing boundaries relevant to census data, such as census tracts, congressional districts, metropolitan and urban areas. 1990-present, dates vary.
- Online Census Tract Maps (MSU LibGuide)Links to census maps in available cities, 1940-2010. Digitized by Michigan State University and Indiana University Bloomingtion.
- Census Bureau Interactive MapsNumerous maps and tools that you can manipulate
- Geocoder Address Lookup (Census Bureau)Look up a single addresses or batches to find out which geographic entities they are located in
- National Historical Geographic Information System (NHGIS)"The National Historical Geographic Information System (NHGIS) provides population, housing, agricultural, and economic data, along with GIS-compatible boundary files, for geographic units in the United States from 1790 to the present."
Understanding how geographic areas are divided and described by the Census Bureau is important for making sure you are selecting the right census data for your purposes. Census geographic boundaries can change from one census to the next. If you are attempting to compare different time periods, use the map resources above to verify that the boundaries have not changed in a way that impacts your analysis.
- Block: The smallest unit of data tabulation
- Block Group: A collection of census blocks that begin with the same first digit of the 4-digit block ID number. Generally between 600-3,000 people.
- Census Tract (formerly known as Block Numbering Areas): Generally between 1,200-8,000 people, ideally 4,000 people. Census tract boundaries are intended to be stable over time, but you should check historical maps to be sure.
- Place: Incorporated places, such as cities or villages, have legal boundaries. Census Designated Places (CDPs) are statistical entities whose boundaries are designated by the Census Bureau, in conjunction with local officials. Many unincorporated communities are not designated CDPs; their data is included in MCDs or CCDs.
- Minor Civil Divisions (MCDs)/Census County Divisions (CCDs): MCDs are subdivisions of a county with legal boundaries, such as townships (towns in Wisconsin.) CCDs are statistical divisions of a county in the 21 states that do not have legally defined MCDs; their boundaries are designated by the Census Bureau, in conjunction with local officials.
- County: The primary division of States. Known by other names in some locations (parish, municipio, etc.).
Some geographic entities cross county lines (metropolitan areas, school districts, etc.). There is not a strict hierarchical relationship between places and counties, but all can be defined by the census blocks that they are comprised of.
Wisconsin Resources
- Applied Population Laboratory, University of Wisconsinconducts additional small area demographic research
- Wisconsin Demographic Services (State Data Center)As part of the Wisconsin Department of Administration, provides additional statistical analyses of Wisconsin census data
1970-future - GetFactsWisconsin's Demographic Data and Visualization Portal
- Guide to State and Local Census Geography byCall Number: Online Access or Click title to check print availabilityContains information about census geography in each state
- (1990) Census Tract Atlas of Wisconsin byCall Number: Click title to check availabilityPublication Date: 1993Detailed maps of urban areas defining the boundaries of census tracts for the 1990 census in Wisconsin.