Polk County
Also known as Polk County, Iowa, Polk County, IA
county in Iowa, United States
Key facts
- Country
- United States
- State
- Iowa
- Founded
- January 13, 1846 (created), March 1, 1846 (organized)
- Named after
- James K. Polk
- Seat
- Des Moines
- Largest city
- Des Moines
- Total
- 591.888 sq mi (1,532.98 km )
- Land
- 572.720 sq mi (1,483.34 km )
- Water
- 19.168 sq mi (49.64 km ) 3.24%
- Estimate 2025
- 516,546
- Density
- 859.759/sq mi (331.955/km )
- Time zone
- UTC−6 ( Central )
- Summer dst
~10 min read
Article
Polk County is a county located in the U.S. state of Iowa. As of the 2020 census, the population was 492,401, and was estimated to be 516,546 in 2025, making it the most populous county in Iowa. The county seat and the largest city is Des Moines, which is also the capital city of Iowa. Polk County is included in the Des Moines–West Des Moines, IA Metropolitan Statistical Area.
History