Polk County is a county in Iowa, United States, centred on Des Moines, the state capital, along the Des Moines and Raccoon rivers. It had a population of 492,401 at the 2020 census and covers 592 square miles (1,533 km2) centred near 41°41′N 93°34′W.
Des Moines is the county seat, and its postal code is 50309. Polk County holds 20 incorporated cities and villages, one census-designated place, and more than 20 unincorporated communities, grouped into 21 civil townships. The county sits in the Central time zone, and its FIPS code is 19153.
Towns & Villages in Polk County
Polk County is Iowa’s most populous county, home to more than 15% of the state’s residents. Its 20 incorporated places range from Des Moines, the state capital, down to villages under 500 people; several — Norwalk, Carlisle and Granger — are primarily seated in neighboring counties but extend into Polk. Saylorville is an unincorporated census-designated place rather than a city. “Unincorp.” below marks a community with no city government of its own.
| Place | Type | Pop. | ZIP |
|---|---|---|---|
| Des Moines | City · seat | 214,133 | 50309 |
| West Des Moines | City | 68,723 | 50265 |
| Ankeny | City | 67,887 | 50021 |
| Urbandale | City | 45,580 | 50322 |
| Johnston | City | 24,064 | 50131 |
| Altoona | City | 19,565 | 50009 |
| Clive | City | 18,601 | 50325 |
| Grimes | City | 15,392 | 50111 |
| Norwalk | City | 12,799 | 50211 |
| Pleasant Hill | City | 10,147 | 50327 |
| Bondurant | City | 7,365 | 50035 |
| Polk City | City | 5,543 | 50226 |
| Windsor Heights | City | 5,252 | 50311 |
| Carlisle | City | 4,160 | 50047 |
| Saylorville | CDP | 3,584 | — |
| Mitchellville | City | 2,485 | 50169 |
| Granger | City | 1,654 | 50109 |
| Alleman | City | 423 | 50007 |
| Runnells | City | 457 | 50237 |
| Elkhart | City | 882 | 50073 |
| Sheldahl | City | 297 | 50201 |
| Camp Dodge | Unincorp. | — | — |
| Crocker | Unincorp. | — | — |
| Herrold | Unincorp. | — | — |
| Berwick | Unincorp. | — | — |
| Norwoodville | Unincorp. | — | — |
| Rising Sun | Unincorp. | — | — |
| Santiago | Unincorp. | — | — |
| Ivy | Unincorp. | — | — |
| Capitol Heights | Unincorp. | — | — |
| Oralabor | Unincorp. | — | — |
Norwalk, Carlisle and Granger are county-line cities: Norwalk and Carlisle sit mainly in Warren County, and Granger mainly in Dallas County, but all three cross into Polk. Sheldahl straddles the Polk–Boone–Story county line.
Townships
Polk County is divided into 21 civil townships. 2020 township-level population is not published in a form this page can verify, so figures are omitted rather than estimated.
| Township | Pop. (2020) | Main settlements |
|---|---|---|
| Allen | — | — |
| Beaver | — | — |
| Bloomfield | — | — |
| Camp | — | Camp Dodge |
| Clay | — | — |
| Crocker | — | Crocker |
| Delaware | — | — |
| Des Moines | — | — |
| Douglas | — | — |
| Elkhart | — | Elkhart |
| Four Mile | — | — |
| Franklin | — | — |
| Jefferson | — | — |
| Lee | — | — |
| Lincoln | — | — |
| Madison | — | — |
| Saylor | — | Saylorville |
| Union | — | — |
| Walnut | — | — |
| Washington | — | — |
| Webster | — | — |
ZIP Codes
- 50309 — Des Moines (downtown)
- 50317, 50315, 50310, 50320 — Des Moines (east side, south side, near-north side and Fort Des Moines neighborhoods)
- 50311 — Windsor Heights and Des Moines’ north side
- 50265, 50266 — West Des Moines
- 50021, 50023 — Ankeny
- 50322 — Urbandale
- 50131 — Johnston
- 50009 — Altoona
- 50325 — Clive
- 50111 — Grimes
- 50327 — Pleasant Hill
- 50035 — Bondurant
- 50226 — Polk City
Des Moines alone carries more than 30 ZIP codes across its neighborhoods; the smaller cities and villages such as Alleman, Elkhart, Mitchellville, Runnells and Sheldahl each use their own post office ZIP not listed above.
Geography
Polk County lies in central Iowa on the till plains left by the last glaciation, mostly level to gently rolling farmland cut by two rivers. The Des Moines River flows southeast through the county and joins the Raccoon River in downtown Des Moines; Saylorville Lake, a Corps of Engineers reservoir on the Des Moines River north of the city, is the county’s largest body of water and a regional recreation area. About 3% of the county is water.
Polk County borders Boone County to the north, Story County to the northeast, Jasper County to the east, Marion County to the southeast, Warren County to the south, Madison County to the southwest, and Dallas County to the west.
Demographics
Polk County had 492,401 residents at the 2020 census, up from prior counts and still Iowa’s most populous county. Des Moines (214,133) and West Des Moines (68,723) are the two largest communities, together holding more than half the county’s population. Median household income runs above the Iowa median of $71,433 in most of the county’s suburbs, though it varies widely between neighborhoods within Des Moines itself. Population density is roughly 860 people per square mile, among the highest of any Iowa county.
Economy & Local Life
Polk County anchors the Des Moines–West Des Moines metro economy, built on insurance and financial services (Principal Financial Group, Wellmark Blue Cross Blue Shield, EMC Insurance, and several others are headquartered in the county), state government, health care (UnityPoint Health and MercyOne both run major Des Moines hospital campuses), and a growing tech and logistics sector along the I-80/I-35 corridor. The Iowa State Fair, held each August on the fairgrounds on Des Moines’ east side, is the county’s single largest annual event and one of the largest state fairs in the country.
History
Polk County was formed on January 13, 1846, and organized on March 1, 1846, shortly before Iowa achieved statehood. It is named for James K. Polk, who was serving as U.S. president at the time of its formation. Fort Des Moines, a U.S. Army post established at the confluence of the Des Moines and Raccoon rivers in 1843, gave the county seat its name and its start as a settlement; the city became Iowa’s state capital in 1857.
Getting There
Interstates 35 and 80 cross in Polk County just north of Des Moines, and Interstate 235 loops through the city center; U.S. Highways 6, 65 and 69 also run through the county.
- Ames — 30 miles north
- Newton — 30 miles east
- Indianola — 20 miles south
- Winterset — 30 miles southwest
Des Moines International Airport (DSM), on the south side of Des Moines, is the county’s and the state’s largest commercial airport.
Frequently Asked Questions
Where is Polk County, Iowa?
It is in central Iowa, centred on Des Moines, the state capital.
What is the population of Polk County?
492,401 at the 2020 census, the largest of any Iowa county.
How big is Polk County?
592 square miles (1,533 km2), of which about 3% is water.
What is the county seat of Polk County?
Des Moines is the county seat and Iowa’s state capital.
How many towns are in Polk County?
20 incorporated cities and villages, one census-designated place, and more than 20 unincorporated communities.
What ZIP codes are in Polk County?
Des Moines alone spans more than 30 ZIP codes; surrounding cities such as Ankeny, West Des Moines and Urbandale each have their own, listed above.
What river runs through Polk County?
The Des Moines River, joined by the Raccoon River in downtown Des Moines, with Saylorville Lake as its major reservoir north of the city.
More counties in this state: Towns and villages in Iowa.