The area of Crawford County was once a part of the empires of three great European powers: Spain, England, and France. These countries did little to govern this territory that was the tribal hunting grounds at various times of the Sioux, the Omaha, and the Otoes. Occasionally the Pottawattamie visited the southern part of the county. Game was plentiful and intrepid French fur traders carried on their activities on the Missouri slope.
The Louisiana Purchase in 1803 brought Crawford County into the United States. President Jefferson sent Meriwether Lewis and William Clark to explore the territory the government had just purchased. They passed through this area and spent a night camped at the mouth of the Boyer River, a well known spot to fur traders and early travelers. Iowa and Crawford County became parts successively of Louisiana, District of Louisiana, Michigan Territory, Wisconsin Territory, Territory of Iowa, and finally the state of Iowa in 1846. The oncoming tide of settlers made it necessary for the Iowa State Legislature to divide the western area of the state into counties in 1851. Crawford was among those created, and was named in honor of a statesman from Georgia who at various times served as U.S. Senator, Secretary of War, Secretary of the Treasury and Minister to France during the first quarter of the 19th century.