[2][3] The area around present-day Onawa was a stopping point in 1804 for Meriwether Lewis and William Clark during their exploration of the newly obtained Louisiana Purchase.

Many years later, that site was memorialized as the Lewis and Clark State Park.

[6] When Ashton (originally called Bloomfield) was named the county seat in the fall of 1854, a log house served as the first courthouse.

That designation was moved to Onawa on April 5, 1858, and the first Monona County Courthouse was completed that same year.

31.00% of all households were made up of individuals, and 17.50% had someone living alone who was 65 years of age or older.

Ticonic The population ranking of the following table is based on the 2020 census of Monona County.

Barack Obama failed to carry the county in both of his electoral victories statewide & nationally, while Donald Trump in 2020 earned the highest percentage of any candidate since Franklin D. Roosevelt in 1932, in spite of his unsuccessful reelection bid.