Nomadic Native Americans lived in North America's Great Plains for millennia. The Kingdom of France claimed ownership of large parts of North America from the 16th to the 18th centuries. Following the French and Indian War, France secretly ceded New France to Spain under the Treaty of Fontainebleau in 1762.

The Third Treaty of San Ildefonso returned most of the land to France in 1802, but Spain retained title to about 7,500 square miles. The majority of modern-day Kansas was purchased from France in 1803, as part of the 828,000 square mile Louisiana Purchase, for 2.83 cents per acre. 

Lawrence is the county seat and the most populous city. Nomadic Native Americans lived in North America's Great Plains for millennia.
The Kingdom of France claimed ownership of large parts of North America from the 16th to the 18th centuries. Following the French and Indian War, France secretly ceded New France to Spain under the Treaty of Fontainebleau in 1762.

The Third Treaty of San Ildefonso returned most of the land to France in 1802, but Spain retained title to about 7,500 square miles. The majority of modern-day Kansas was purchased from France in 1803, as part of the 828,000 square mile Louisiana Purchase, for 2.83 cents per acre. Douglas County has been dominated by the Democratic Party in recent years, particularly since the 1990s.

Democrats control all county-wide offices. Douglas County is currently represented by Democratic county commissioners Patrick Kelly, Shannon Reid, and Shannon Portillo. According to the Kansas Secretary of State's office, the county had 35,146 registered Democrats, 22,324 registered Republicans, 900 registered Libertarians, and 21,474 registered Independents as of July 2021.

The Kansas Pacific, Douglas County's first railroad, was built through that territory in 1864. Douglas County's political history is more akin to that of Vermont and Maine than the Great Plains. This is because the county has deep New England roots. It supported the Republican candidate in every Presidential election between 1864 and 1960, with the exception of 1912, when the Republican Party was deeply divided and the county backed Progressive Theodore Roosevelt.

Roosevelt would later rejoin the Republican Party. Between 1920 and 1960, the county reverted to form, giving Republican presidential nominees more than 60% of the vote in every election (except 1932 when Herbert Hoover received 58.7 percent). To demonstrate how deeply the county's Republican roots ran, even when Franklin D. Roosevelt's landslide victories in 1932 and 1936 swept Kansas, Republican candidates carried the state.