COUNTY · IN

Marion County, Indiana

Marion County is a county in Indiana with FIPS code 18097 and an estimated population of 968,460 (Census 2023), 1st largest of 92 in the state.

County facts

Name: Marion County
State: Indiana
Type: county
FIPS code: 18097
State FIPS: 18
Population (2023): 968,460
Change since 2020: -0.8%
State rank: 1 of 92

Population is the Census Bureau’s Vintage 2023 estimate.

Major cities in Marion County

Indianapolis

Other counties in Indiana

Lake County Allen County Hamilton County St. Joseph County Elkhart County Tippecanoe County Hendricks County Vanderburgh County All 92

Questions

What is the FIPS code for Marion County?

Marion County, Indiana has the five-digit FIPS code 18097: 18 for the state and 097 for the county.

What state is Marion County in?

Marion County is in Indiana.

How do I know if an address is in this county?

Use the address lookup. ZIP codes and city names can cross county lines, so an address is the reliable check.

Sources: U.S. Census Bureau geographic reference files; Census Bureau Population Estimates, Vintage 2023. Last reviewed 2026-10-27.