Arnegard was founded in 1906 and is named for Evan Arnegard, the first homesteader in the area. The first church was a one-room log cabin, the Wilmington Lutheran Church. It was so named because most of the people who founded Arnegard came from Spring Grove, Minnesota, where they belonged to the Old Wilmington Lutheran Church. The post office was established July 14, 1906 with Gerhard A. Stenehjem as postmaster. The town was incorporated in 1913 when the Great Northern Rail Road extended its line past Watford City to Arnegard.