Census Data

Census data can be organized into two main categories: 1) information about the location and shape of areas; such as counties, tracts and blocks, and 2) information about demographic and economic characteristics of those areas; such as population, housing and income.  These two categories may be thought of as 1) Census Geography and 2) Census Statistics.  Within a state, the U.S. Census Bureau delineates four units of census geography: Counties are divided into Census Tracts, which are made up of Block Groups.  Block groups are further subdivided into individual Blocks (see diagram on page 14 of the  Minnesota Geographic Data Catalog 1998).  All census geography areas lie completely within a single county. 

A different type of area, the Minor Civil Division, is often related to census geography.  In Minnesota, MCDs refer to townships and cities.  They can cross county boundaries and can contain a number of census blocks, block groups and, if large enough, census tracts.  The U.S. Census Bureau provides a single vector data set composed of a variety of geographic features - roads, railroads, rivers, lakes - together with boundaries for all census geography areas.  That collection is called a TIGER/Line file.  TIGER stands for Topologically Integrated Geographic Encoding and Referencing. 

Although filled with an assortment of valuable information, TIGER/Line files are quite large and can be difficult to work with.  As a convenience to GIS users, Minnesota's Legislative GIS Office and the Minnesota Land Management Information Center (LMIC) have refined the TIGER/Line files prepared for the 1990 decennial census by creating separate data files for each level of census geography.  In addition, files for MCDs, school districts, and legislative and congressional districts within Minnesota are also available.  Below are descriptions of census geography data separated by area, TIGER/Line files, and sources for census statistics. 
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Census Geography - Separated by Area
The source for the following data sets are U.S. Census Bureau  TIGER/Line files processed by the Minnesota Legislative GIS Office.  The data are in ARC/INFO export format and there is full state coverage.  The following 5 data sets are available for free via an online linkage in the metadata record: 

Minnesota County Boundaries (1990 Census) - NAD27 version
Minnesota County Boundaries (1990 Census) - NAD83 version
State of Minnesota Legislature - Senate District Boundaries - 1994
State of Minnesota Legislature - House of Representatives District Boundaries - 1994
United States Congressional Districts within the State of Minnesota - 1994

The following data sets are available for a fee from the Minnesota Land Management Information Center (LMIC), 651-296-1211.  File units and prices per unit are in parentheses. 

1990 Tracts (state; $95)
1990 Block Groups (state; $95)
1990 Blocks (county; $95 for first unit; $5 for each additional unit)
1990 Minor Civil Divisions (state; $95) - MCD is available in two versions: with or without county boundaries.  Note: The county boundary version is required to match 1990 census statistics.
1990 or 1997 School Districts (state; $95) - Note: The 1990 version is required to match 1990 census statistics.
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Census Geography - TIGER/Line Files
The term TIGER (Topologically Integrated Geographic Encoding and Referencing) is the name for the system and digital database developed at the U.S. Census Bureau to support its mapping needs for the Decennial Census and other Bureau programs.  A TIGER/Line file is a single layer that contains lines for all census data collection areas.  Lines are assigned codes that indicate the type of boundary or boundaries they represent and the type of feature they portray (roads, railroads, rivers, lakes).  For example, a single line could be coded as a county and census tract boundary, and also as a river.  Using these line codes, GIS users can select features they want to analyze.  The census distributes the TIGER/Line files and publishes on-line technical documentation that explains format and translates codes.  Although line files can be complicated, they are sometimes the only source for geocode address information.  Note: Many areas, particularly rural parts of the state, do not have complete address information.  TIGER/Line files may be ordered via the TIGER Page, or by contacting the U.S. Census Bureau Customer Services Office, 301-457-4100. 

The Minnesota Land Management Information Center (LMIC) distributes a version of the TIGER/Line data set in ARC/INFO format that includes 1992 file updates and corrections, primarily additional address range information.  The U.S. Census Bureau has prepared more recent updates, but these have not been incorporated into LMIC files.  This data set can be ordered by contacting LMIC, 651-296-1211.  The file unit is by county and the price is $95 for the first unit; $15 for each additional unit. 
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Census Statistics
The Minnesota Land Management Information Center's (LMIC)DATANET system provides on-line viewing and downloading of selected census statistics. 

The U.S. Census Bureau Customer Services Office (301-457-4100) provides a wide range of census products and maintains a list of private vendors who have repackaged census data. 

Another valuable source of census information is the University of Minnesota's Machine Readable Data Center.  The center is a coordinating member of the Minnesota State Data Center and serves as the tape depository for that network.  Located on the University's Minneapolis campus, the center provides assistance in using its extensive collection, as well as customized consulting on a fee-for-service basis.  It is open to the general public.  For more information, contact the center at mrdc@mrdc.lib.umn.edu or 612-624-4389.
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