Decatur had arrived in the area of the town from Bellevue in the 1840s and made his home with the Omaha tribe. Later he was a clerk at Sarpy's trading post and lived on a farm which was called "Decatur Springs," owing to the pure spring found there.
The town of Decatur was incorporated in 1856 under the name "The Decatur Townsite & Ferry Company." The other incorporators included Thomas Whiteacre, T. H. Hineman, George Mason, and Herman Glass. The patents for the town were granted on May 1, 1862.