[3] Butler County was formed on January 15, 1851, from open land.

It was named after Kentucky native William Orlando Butler, a general and hero of the Mexican–American War, who ran as Vice President of the United States in 1848.

The first court proceedings were conducted in a small log cabin of a settler.

Because locals became disenchanted with Butler Center (partially because of its inaccessibility during the winter), Allison was made the county seat on January 10, 1881, after the tracks of the Dubuque and Dakota Railroad had been laid there.

[11] As of the census[12] of 2000, there were 15,305 people, 6,175 households, and 4,470 families residing in the county.

25.00% of all households were made up of individuals, and 14.50% had someone living alone who was 65 years of age or older.

Since the county's founding in 1851, it has only favored candidates of another party four times.

The first occasion was in 1912, when former Republican Theodore Roosevelt won the county as the Progressive candidate.

Finally, the most recent occurrence was in 1996, when incumbent Bill Clinton won the county with a plurality, aided in part by a strong third party performance by Ross Perot; furthermore, Clinton only defeated Republican candidate Bob Dole in Butler County by just 25 votes and a slim margin of 0.38%.