[2] The county is named for Colonel John Allen, a state senator and soldier who was killed leading the 1st Regiment of Kentucky Rifleman at the Battle of Frenchtown, Michigan during the War of 1812.

Allen County is included in the Bowling Green, KY Metropolitan Statistical Area.

A courthouse fire in 1902 resulted in the loss of some county records.

[6] As of the census of 2000, there were 17,800 people, 6,910 households, and 5,113 families residing in the county.

23.10% of all households were made up of individuals, and 10.40% had someone living alone who was 65 years of age or older.