Like many towns in Montana, this one was named by railroad officials. It was a rye field on the Sims-Garfield ranch that was the inspiration for the name. The town is built at the base of a three-mile-long stretch of rimrocks on what was once part of that ranch.
These rimrocks were once the shore of a large lake. As a result, the area is a good place to hunt for marine fossils. The rimrocks themselves still have a number of prehistoric inscriptions visible, including a crudely drawn picture of six men and three antelope. Ruth Lane Garfield was the first woman sheriff in Montana and had her office in Ryegate. She was appointed to fill out her husband’s position after he was shot by a demented farmer in 1920.