Ohio Counties by Population (2025)

There are 88 counties in Ohio.

Franklin County, home of Columbus, has the highest population in Ohio with 1,310,300 residents. This represents growth of 12.35% since the last census.

The next-largest counties are:

• Cuyahoga County (1,243,857) with Cleveland
• Hamilton County (816,684) with Cincinnati
• Summit County (541,918)
• Montgomery County (532,331)

These are the only counties in Ohio exceeding 500,000 residents. Of these counties, Franklin County experienced the most rapid growth while Cuyahoga County experienced growth of -2.68%.

Counties with Fewest Residents

There are no counties in Ohio with fewer than 10,000 residents. The least populated county in Ohio is Vinton County with 13,139, a decline of 1.98%.

Other small counties in Ohio include:

• Monroe County (13,790)
• Noble County (14,354)
• Morgan County (14,604)
• Harrison County (15,174)
• Paulding County (18,760)

All of these counties have experienced a decline in population. Monroe County had the largest decline of 5.60%. Of Ohio‘s 39 counties with a population below 50,000, all but five experienced a decline in population ranging from -0.02% to -6.12% in the case of Carroll County.

Counties with Rapid Growth

Delaware County experienced the most rapid growth in the state since the last census, climbing 16.98% to 204,826 residents.

Other counties with major growth include:

• Franklin County (12.35%)
• Union County (10.35%)
• Warren County (8.77%)
• Fairfield County (6.41%)

The counties with the most rapid decline are:

• Carroll County (-6.12%)
• Jefferson County (-5.60%)
• Monroe County (-5.60%)
• Trumbull County (-5.34%)