Madison, WI
Metropolitan Statistical Area
MSA code 31540 is the Madison, WI, a Metropolitan Statistical Area defined by the Office of Management and Budget (OMB). It encompasses 4 counties. This code is used by the BLS, Census Bureau, HUD, and BEA to publish labor market, demographic, and economic data at the metropolitan area level — distinct from the individual county FIPS codes used for county-level data.
MSA Code
31540
Type
Metro SA
Component Counties (4)
OMB designates each county in a Core Based Statistical Area as either central — containing the urban core that anchors the metro — or outlying, meaning it qualifies based on commuting ties to the central counties. Both types are included in MSA-level data published by federal agencies. Click any county to see its individual 5-digit FIPS code and data profile.
| County | FIPS Code |
|---|---|
| Dane County | 55025 |
| Columbia County | 55021 |
| Green County | 55045 |
| Iowa County | 55049 |
Federal Datasets Using MSA Code 31540
Several major federal datasets publish directly at the MSA level using this 5-digit code rather than individual county FIPS codes. Note that MSA codes and county FIPS codes are separate namespaces — never join an MSA code against a county FIPS column. To work with county-level data within this metro, use the individual county FIPS codes listed above.