Grassy Butte is an unincorporated community in southeastern McKenzie County, North Dakota, United States. It lies along U.S. Route 85 south of the city of Watford City, the county seat of McKenzie County. Its elevation is 2,661 feet (811 m). Although it is unincorporated, it has a post office, with the ZIP code of 58634. Grassy Butte currently has a gas station/convenience store and a bar. The elementary school was closed and the property sold. The residents now have the choice to send their children to Killdeer, Watford City or Belfield schools. The town also houses many different businesses including a welding production shop, construction companies and a tractor repair shop.