Ainsworth is named for Captain James E. Ainsworth. Captain Ainsworth was the chief construction engineer of the Fremont, Elkhorn and Missouri Valley Railroad. He arrived at the town site in June 1882. 160 acres of free land was claimed under certain provisions that improvements be made specified by the government. Ainsworth was platted in 1883 and was incorporated as a village in December 1883.
Churches started being built in 1881 starting with the Methodist and followed by the Congregational-United Church of Christ in 1883. By 1884 a two-story red-brick grade school was built that stood until 1955 before being replaced. The first Courthouse came in 1888 which served the county until Easter morning in 1958 when it was tragically destroyed by a fire. Most of the records that were stored in vaults were saved and the new courthouse was dedicated on June 12th, 1960.