Indiana Counties by Population (2025)

There are 92 counties in Indiana.

Marion County is the largest county in the state, with a population of 987,602. The most recent census shows that its population has increased by 0.01% since the previous census.

A number of other Indiana counties also boast relatively large populations for their state, though not able to match the density of Marion County:

• Lake County : 505,319
• Allen County : 403,459

Indiana Counties with the Fewest Residents

The smallest county in Indiana is Ohio County , with a population of just 5,999. This total represents a increase of 0.0% since the last census count was performed.

Other small counties include:

• Union County : 6,796
• Warren County : 8,404
• Benton County : 8,945

Indiana Counties with Rapid Growth

Boone County , with its current population of 81,351, has shown the largest population growth, with an increase of 0.1% since the last census.

Lake County has also had relatively high population growth of 0.01% with 505,319 residents.

On the other hand, Union County has had the largest decrease in population, with its 6,796 current residents totalling 0.0% less than the previous census.