Oklahoma Counties by Population (2025)

There are 77 counties in Oklahoma.

Oklahoma County is the largest county in the state, with a population of 821,884. The most recent census shows that its population has increased by 0.03% since the previous census.

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

• Tulsa County : 700,617
• Cleveland County : 305,991

Oklahoma Counties with the Fewest Residents

The smallest county in Oklahoma is Cimarron County , with a population of just 2,078. This total represents a decrease of 0.1% since the last census count was performed.

Other small counties include:

• Harmon County : 2,221
• Harper County : 3,211
• Roger Mills County : 3,277

Oklahoma Counties with Rapid Growth

Canadian County , with its sizeable population of 187,336, has shown the largest population growth, with an increase of 0.2% since the last census.

Tulsa County has also had relatively high population growth of 0.04% with 700,617 residents.

On the other hand, Harmon County has had the largest decrease in population, with its 2,221 current residents totalling 0.1% less than the previous census.