Grant County, Indiana

Grant County, Indiana
Grant County Courthouse in Marion
Location within the U.S. state of Indiana
Coordinates: 40°31′N 85°39′W / 40.52°N 85.65°W / 40.52; -85.65
Country United States
State Indiana
Founded1831
Named afterSamuel and Moses Grant
SeatMarion
Largest cityMarion
Area
 • Total
414.90 sq mi (1,074.6 km2)
 • Land414.07 sq mi (1,072.4 km2)
 • Water0.82 sq mi (2.1 km2)  0.20%
Population
 (2020)
 • Total
66,674
 • Estimate 
(2025)
66,615
 • Density161.02/sq mi (62.171/km2)
Time zoneUTC−5 (Eastern)
 • Summer (DST)UTC−4 (EDT)
Congressional district5th
Websitewww.grantcounty.net
Indiana county number 27

Grant County is a county in central Indiana in the United States Midwest. At the time of the 2020 census, the population was 66,674. The county seat is Marion. Important paleontological discoveries, dating from the Pliocene epoch, have been made at the Pipe Creek Sinkhole in Grant County.