The following links provide detailed geographic information available in select IPUMS samples. 

Geography Of The Federal Census

County Composition of Nineteenth Century Metropolitan Areas, 1850-1990

County Composition of All Metropolitan Areas, 1900-1990

ICPSR County Codes

State Economic Area Codes

County Composition of 1970 Metropolitan Areas

County Composition of 1970 County Groups

1970 Neighborhood Characteristics

1970 County Group Maps

1980 County Group Maps and Detailed Composition

1990 PUMA Maps and Detailed Composition

1990 Consolidated Metropolitan Areas

Detailed Geographic Codes, 1850-1920

1990 1% Metro Sample Interstate PUMAs ("99" file)

The following links provide detailed geographic information in machine-readable (ASCII) format
(NOTE: These files are in ZIP format--you will need to use decompression software to open the files)

• 1980 County Groups - Detailed Composition (1% metro sample)
• 1980 County Groups - Detailed Composition (5% state sample)
• 1990 PUMAs - Detailed Composition (1% metro sample)
• 1990 PUMAs - Detailed Composition (5% state sample, 3% elderly sample)
• 1990 Planning Service Areas - County Composition (3% elderly sample)