List of counties in Iowa

Geography and size

County land area in Iowa varies considerably. The Iowa Constitution set minimum area requirements when the state organized its local governments; nevertheless, ten counties fall below that prescribed minimum due to historical exceptions. The smallest county by land area is Dickinson County (about 381 square miles), while the largest is Kossuth County (about 973 square miles). Polk County, which contains the state capital and largest city, Des Moines, is the most densely populated county in Iowa.

History and development

Two of the earliest county organizations in the territory were Des Moines County and Dubuque County, both created in 1834 when the area was administered as part of the Michigan Territory. County formation continued as settlement spread: a notable event took place on January 15, 1851, when a large number of counties were established, creating much of the framework for the present 99 counties. The Iowa Constitution of 1857 further defined county boundaries, powers and minimum sizes.

Government, seats and services

Each county usually contains a county seat, the town where the courthouse and main administrative offices are located. County governments prepare budgets, levy property taxes within state limits, maintain local roads and bridges, oversee law enforcement and support social services. They also perform vital record functions (birth, death and marriage certificates) and manage land records used in property transactions.

Notable facts and uses

• The 99‑county structure is central to how Iowa organizes elections, public records and many state‑local interactions.
• Area and population vary from very rural counties with sparse populations to urbanized counties centered on Des Moines and other cities.
• County boundaries and names reflect settlement patterns, Native American geography, early explorers and political decisions made during the 19th century.

Where to find more information

For official lists, maps and current statistics consult state and county publications, county websites and compiled directories that provide county seats, population estimates and contact information. State archives and historical societies also document the origins and changes of counties over time. For quick reference and further reading see state summaries under the headings: U.S. state government sources and county directories linked from state portals.