Crawford County is a county located in the U.S. state of Iowa. As of the 2020 census, the population was 16,525. Its county seat is Denison. The county was named for William Harris Crawford, U.S. senator from Georgia and United States Secretary of the Treasury.

In January 1851, the Iowa Legislature authorized the creation of 50 additional counties in the state. Due to its lack of inhabitants, the designated Crawford County area was attached to Shelby County for purposes of revenue, taxation, and judicial matters.

In 1855 there were sufficient settlers, who petitioned for separation from Shelby. This was granted, and a county governing structure was established. The county as then designated did not include its present western townships.

In 1865, four eastern townships of Monona County were separated from that county and incorporated into Crawford County's boundary.

After several adjustments and reorganizations, the present arrangement of Crawford County townships was completed in June 1872.

According to the US Census Bureau, the county has a total area of 715 square miles (1,850 km²), of which 714 square miles (1,850 km²) is land and 0.8 square miles (2.1 km²) (0.1%) is water.

The 2020 census recorded a population of 16,525 in the county, with a population density of 23.1349/sq mi (8.93244/km²). 89.34% of the population reported being of one race. There were 6,855 housing units of which 6,255 were occupied.

The 2010 census recorded a population of 17,096 in the county, with a population density of 23.944/sq mi (9.245/km²). There were 6,943 housing units, of which 6,413 were occupied.