Largest Counties in Iowa

Originally part of the Louisiana Purchase, Iowa became a state in 1846. It has been a key agricultural state throughout its history. Iowa has 99 counties.

10 Largest Counties in Iowa

1. Polk County

County Facts

  • Population: 492,401 (2020 Census)
  • Area Codes: 515
  • ZIP Codes: 50009-50398
  • County Seat: Des Moines

Geography and History

Polk County, located in central Iowa, spans 591 square miles and is home to the state capital, Des Moines. Established in 1846, the county was named after James K. Polk, the 11th President of the United States. Its location at the confluence of the Des Moines and Raccoon Rivers made it a strategic site for trade and transportation in its early years. The economy was initially based on agriculture and mining, but Des Moines quickly grew into a financial and insurance hub, leading to significant urban development. Today, Polk County is the most populous in the state, with a diverse economy that includes government, education, and technology sectors.

Colleges and Universities

  • Drake University: A private university in Des Moines known for its law school, business, and education programs.
  • Des Moines Area Community College (DMACC): A community college offering a wide range of vocational and academic programs.
  • Grand View University: A private liberal arts university with strong programs in nursing, business, and education.
  • Iowa State University (Extension Programs): Although based in Ames, Iowa State offers outreach and extension services throughout Polk County.

Major Landmarks

Polk County is home to iconic landmarks such as the Iowa State Capitol, a stunning building known for its gold dome. Gray’s Lake Park offers scenic walking trails and paddleboarding near downtown Des Moines. The Des Moines Art Center features a renowned collection of modern and contemporary art. The Pappajohn Sculpture Park is a vibrant outdoor space with large-scale sculptures. Adventureland Park is a major amusement park located in Altoona, while Blank Park Zoo offers family-friendly animal exhibits. The Iowa State Fairgrounds hosts one of the largest state fairs in the country. Principal Park is home to the Iowa Cubs, the Triple-A affiliate of the Chicago Cubs.


2. Linn County

County Facts

  • Population: 230,299 (2020 Census)
  • Area Codes: 319
  • ZIP Codes: 52202-52499
  • County Seat: Cedar Rapids

Geography and History

Linn County is located in eastern Iowa and covers 726 square miles. It was established in 1839 and named after Senator Lewis F. Linn of Missouri. The Cedar River runs through the county, contributing to its development as a center for industry and transportation. Cedar Rapids, the county seat, grew into a major city due to its location on the river, which helped facilitate grain milling and other industries. Over time, Linn County has diversified its economy, which now includes manufacturing, finance, and technology. The area’s rich history includes Native American settlements, as well as waves of European immigration that contributed to its cultural landscape.

Colleges and Universities

  • Coe College: A private liberal arts college in Cedar Rapids known for its programs in the sciences, arts, and business.
  • Kirkwood Community College: One of Iowa’s largest community colleges, offering vocational training, associate degrees, and continuing education programs.
  • Mount Mercy University: A private Catholic university with strong programs in nursing, business, and social sciences.

Major Landmarks

Linn County is home to cultural and historical landmarks such as Brucemore, a historic mansion and estate offering tours and events. The National Czech & Slovak Museum & Library in Cedar Rapids celebrates the heritage of Czech and Slovak immigrants to the area. Indian Creek Nature Center provides hiking and educational programs focused on local ecology. The Cedar Rapids Museum of Art has the world’s largest collection of works by Grant Wood, the artist behind “American Gothic.” Palisades-Kepler State Park offers camping, hiking, and scenic views along the Cedar River. NewBo City Market is a vibrant marketplace for local food and crafts in the New Bohemia District.


3. Scott County

County Facts

  • Population: 174,669 (2020 Census)
  • Area Codes: 563
  • ZIP Codes: 52701-52809
  • County Seat: Davenport

Geography and History

Scott County, located in eastern Iowa along the Mississippi River, covers 468 square miles. It was established in 1837 and named after General Winfield Scott, a hero of the War of 1812. The county’s location on the Mississippi made it an early hub for river trade, which contributed to the rapid growth of its largest city, Davenport. Scott County’s economy was historically driven by agriculture, manufacturing, and transportation. Today, it is part of the Quad Cities metropolitan area, which includes neighboring cities in Illinois, making it a vibrant commercial and cultural center.

Colleges and Universities

  • St. Ambrose University: A private Catholic university located in Davenport, known for its programs in health sciences, business, and liberal arts.
  • Eastern Iowa Community Colleges: A network of community colleges offering a variety of technical and academic programs throughout the region.
  • Palmer College of Chiropractic: Located in Davenport, Palmer is the world’s first chiropractic school and remains a leader in the field.

Major Landmarks

Scott County features several prominent landmarks, including the Figge Art Museum, which houses a diverse collection of American, European, and contemporary art. Vander Veer Botanical Park in Davenport offers beautiful gardens and walking paths. The Putnam Museum and Science Center provides exhibits on history, culture, and natural science. Modern Woodmen Park is a historic baseball stadium along the Mississippi River and home to the Quad Cities River Bandits minor league baseball team. Credit Island Park offers recreational activities and historical significance, as it was a battlefield during the War of 1812. The Quad City Symphony Orchestra and Adler Theatre host performances and events year-round.


4. Black Hawk County

County Facts

  • Population: 131,144 (2020 Census)
  • Area Codes: 319
  • ZIP Codes: 50613-50707
  • County Seat: Waterloo

Geography and History

Black Hawk County is located in northeastern Iowa, covering 573 square miles. Established in 1843, the county is named after Black Hawk, a leader of the Sauk Native American tribe. The Cedar River runs through the county, with Waterloo and Cedar Falls being its largest cities. Black Hawk County became a significant industrial center in the late 19th and early 20th centuries, driven by agricultural production and manufacturing. Today, the county has a diversified economy, with education, healthcare, and technology contributing to its growth. Cedar Falls is home to the University of Northern Iowa, which plays a major role in the region’s education and culture.

Colleges and Universities

  • University of Northern Iowa (UNI): A public university in Cedar Falls, known for its programs in education, business, and performing arts.
  • Hawkeye Community College: A community college located in Waterloo, offering vocational and academic programs, including associate degrees and certificates.
  • Allen College: A health sciences-focused institution offering nursing and radiologic science programs.

Major Landmarks

Black Hawk County is home to landmarks such as the John Deere Tractor & Engine Museum, which showcases the area’s agricultural and industrial heritage. The Grout Museum District in Waterloo includes history, science, and military exhibits. The Ice House Museum in Cedar Falls preserves the history of the ice industry in Iowa. The Hearst Center for the Arts in Cedar Falls offers galleries, studios, and performance spaces. George Wyth State Park is a popular destination for camping, hiking, and water recreation. The Cedar Valley Nature Trail provides scenic biking and hiking paths, connecting communities across the county.


5. Johnson County

County Facts

  • Population: 152,854 (2020 Census)
  • Area Codes: 319
  • ZIP Codes: 52240-52338
  • County Seat: Iowa City

Geography and History

Johnson County is located in eastern Iowa and covers 623 square miles. Established in 1837, the county was named after Richard Mentor Johnson, the ninth Vice President of the United States. Iowa City, the county seat, was the first capital of Iowa and remains an important educational and cultural center as the home of the University of Iowa. Historically, the county’s economy was based on agriculture, but the presence of the university has shaped its development, making education, healthcare, and technology key drivers of growth.

Colleges and Universities

  • University of Iowa: A flagship public research university known for its programs in law, medicine, and creative writing, including the famous Iowa Writers’ Workshop.
  • Kirkwood Community College (Iowa City Campus): Offers associate degrees and vocational programs with a focus on serving local industries and businesses.
  • Allen College (Satellite Programs): Provides health sciences education, particularly in nursing and radiologic technology.

Major Landmarks

Johnson County is home to cultural and historical landmarks such as the Old Capitol Building, which served as the original seat of Iowa’s government and is now part of the University of Iowa’s campus. The Iowa Museum of Natural History showcases exhibits on the state’s natural history. The Herbert Hoover Presidential Library and Museum is located nearby in West Branch. The Iowa River Landing area in Coralville offers shopping, dining, and entertainment, as well as the Coralville Center for the Performing Arts. Lake Macbride State Park provides opportunities for camping, boating, and hiking, while The Devonian Fossil Gorge offers a glimpse into the state’s ancient geological history.


6. Woodbury County

County Facts

  • Population: 105,941 (2020 Census)
  • Area Codes: 712
  • ZIP Codes: 51001-51111
  • County Seat: Sioux City

Geography and History

Woodbury County is located in western Iowa along the Missouri River, covering 874 square miles. Established in 1851, it was named after Levi Woodbury, a U.S. Supreme Court Justice. Sioux City, the county seat, developed as a transportation hub in the 19th century due to its location on the river. The economy of Woodbury County has historically been centered on meatpacking and agriculture, but today it includes healthcare, education, and manufacturing. Sioux City remains a vibrant cultural and economic center in western Iowa, serving as a regional hub for commerce and industry.

Colleges and Universities

  • Morningside University: A private university known for its programs in education, business, and nursing.
  • Western Iowa Tech Community College: A public community college offering associate degrees and technical programs in fields like healthcare, technology, and skilled trades.
  • Briar Cliff University: A private Catholic university offering undergraduate and graduate programs in business, education, and the liberal arts.

Major Landmarks

Woodbury County is home to landmarks such as the Sergeant Floyd Monument, a tribute to the only member of the Lewis and Clark Expedition to die during the journey. The Orpheum Theatre in Sioux City is a beautifully restored venue for concerts and performances. The Sioux City Public Museum offers exhibits on regional history and culture. Stone State Park provides hiking trails and scenic views of the Loess Hills. The Art Center of Sioux City showcases modern and contemporary art. Lewis and Clark Interpretive Center and Betty Strong Encounter Center offer educational programs about the explorers’ journey. The Sioux City Railroad Museum preserves the area’s railroading heritage.


7. Dubuque County

County Facts

  • Population: 99,266 (2020 Census)
  • Area Codes: 563
  • ZIP Codes: 52001-52099
  • County Seat: Dubuque

Geography and History

Dubuque County is located in northeastern Iowa along the Mississippi River, covering 617 square miles. Established in 1834, it is named after Julien Dubuque, a French-Canadian fur trader and the first European settler in the region. Dubuque, the county seat, is one of Iowa’s oldest cities and played a significant role in the state’s early development, driven by lead mining, agriculture, and river trade. Today, Dubuque County has a diverse economy that includes manufacturing, education, healthcare, and tourism, and it remains a key part of Iowa’s economic and cultural landscape.

Colleges and Universities

  • University of Dubuque: A private Presbyterian university offering programs in aviation, business, and the liberal arts.
  • Clarke University: A private Catholic university with strong programs in nursing, physical therapy, and education.
  • Loras College: A private Catholic liberal arts college known for its programs in political science, business, and education.

Major Landmarks

Dubuque County is known for its scenic beauty and historic landmarks, including the Fenelon Place Elevator, one of the world’s shortest and steepest railways, offering panoramic views of the Mississippi River. The National Mississippi River Museum & Aquarium showcases the river’s ecology and history. Eagle Point Park provides stunning views of the river and the tri-state area. The Dubuque Arboretum & Botanical Gardens offers beautifully landscaped gardens. Crystal Lake Cave is a popular tourist attraction known for its stunning underground formations. Mathias Ham House is a historic mansion, while Field of Dreams Movie Site in nearby Dyersville draws visitors from around the world.


8. Story County

County Facts

  • Population: 98,537 (2020 Census)
  • Area Codes: 515
  • ZIP Codes: 50010-50278
  • County Seat: Nevada

Geography and History

Story County is located in central Iowa, covering 574 square miles. The county was established in 1846 and named after Supreme Court Justice Joseph Story. The presence of Iowa State University in Ames has been a driving force behind the county’s development, making education, research, and technology key components of its economy. Story County was historically an agricultural area, but the university’s influence has led to diversification, particularly in biotechnology, engineering, and advanced manufacturing. The county also benefits from its location along major transportation routes, including Interstate 35.

Colleges and Universities

  • Iowa State University (ISU): A major public research university located in Ames, known for its programs in agriculture, engineering, and veterinary medicine.
  • Des Moines Area Community College (Ames Campus): Offers vocational programs, associate degrees, and workforce training in collaboration with Iowa State University.
  • College of Veterinary Medicine (ISU): One of the leading veterinary schools in the U.S., affiliated with Iowa State University.

Major Landmarks

Story County is home to Iowa State University, with landmarks like the Campanile and Reiman Gardens, a beautiful botanical garden and butterfly conservatory. The Iowa State Center hosts cultural performances, while Jack Trice Stadium is home to ISU’s football team. Ada Hayden Heritage Park offers scenic walking trails and fishing opportunities. Boone Scenic Valley Railroad provides historical train rides through the countryside. Hickory Grove Park is a popular spot for camping, swimming, and hiking. The ISU Research Park fosters innovation and technology startups, contributing to the region’s reputation as a hub for science and research.


9. Pottawattamie County

County Facts

  • Population: 93,667 (2020 Census)
  • Area Codes: 712
  • ZIP Codes: 51501-51576
  • County Seat: Council Bluffs

Geography and History

Pottawattamie County is located in southwestern Iowa along the Missouri River, covering 951 square miles. Established in 1848, the county is named after the Pottawattamie Native American tribe. Council Bluffs, the county seat, was a major stopping point for westward pioneers and served as a key hub for transportation and trade due to its location on the river. The construction of the transcontinental railroad solidified Council Bluffs’ importance in the region. Today, the county has a diverse economy, including manufacturing, logistics, and tourism, with strong ties to nearby Omaha, Nebraska.

Colleges and Universities

  • Iowa Western Community College: A public institution in Council Bluffs offering associate degrees and vocational training in fields such as healthcare, technology, and business.
  • University of Nebraska at Omaha (Partnership Programs): Although based in Omaha, the university collaborates with Iowa Western Community College on joint degree programs and continuing education initiatives.

Major Landmarks

Pottawattamie County is home to several historical and natural landmarks, including the Union Pacific Railroad Museum, which celebrates the history of the transcontinental railroad. The Lewis and Clark Monument offers scenic views of the Missouri River and commemorates the explorers’ journey. Bayliss Park in downtown Council Bluffs features a fountain and hosts community events. The Squirrel Cage Jail, a rare rotary jail, is a historic site and museum. Lake Manawa State Park offers boating, swimming, and hiking. Hitchcock Nature Center provides hiking trails and educational programs in the scenic Loess Hills.


10. Dubuque County

County Facts

  • Population: 99,266 (2020 Census)
  • Area Codes: 563
  • ZIP Codes: 52001-52099
  • County Seat: Dubuque

Geography and History

Dubuque County is located in northeastern Iowa along the Mississippi River, covering 617 square miles. Established in 1834, it is named after Julien Dubuque, a French-Canadian fur trader and the first European settler in the region. Dubuque, the county seat, is one of Iowa’s oldest cities and played a significant role in the state’s early development, driven by lead mining, agriculture, and river trade. Today, Dubuque County has a diverse economy that includes manufacturing, education, healthcare, and tourism, and it remains a key part of Iowa’s economic and cultural landscape.

Colleges and Universities

  • University of Dubuque: A private Presbyterian university offering programs in aviation, business, and the liberal arts.
  • Clarke University: A private Catholic university with strong programs in nursing, physical therapy, and education.
  • Loras College: A private Catholic liberal arts college known for its programs in political science, business, and education.

Major Landmarks

Dubuque County is known for its scenic beauty and historic landmarks, including the Fenelon Place Elevator, one of the world’s shortest and steepest railways, offering panoramic views of the Mississippi River. The National Mississippi River Museum & Aquarium showcases the river’s ecology and history. Eagle Point Park provides stunning views of the river and the tri-state area. The Dubuque Arboretum & Botanical Gardens offers beautifully landscaped gardens. Crystal Lake Cave is a popular tourist attraction known for its stunning underground formations. Mathias Ham House is a historic mansion, while Field of Dreams Movie Site in nearby Dyersville draws visitors from around the world.