Roundup is a city in and the county seat of Musselshell County, Montana, United States. The population was 1,788 during the 2010 census.
Roundup is located at 46°26′54″N 108°32′34″W (46.448401, -108.542676). According to the United States Census Bureau, the city has a total area of 1.34 square miles (3.47 km2), all land.
The Musselshell River runs through the city. Roundup is bordered to the south by the Bull Mountains which rise from the great plains over a hundred miles east of the front range of the Rocky Mountains.
Roundup served as a place for cattlemen to "round up" their cattle along the Musselshell River. It was the trailhead in the Great Montana Centennial Cattle Drive and now drives happen annually.
The area has coal mines, which combined with the agriculture, maintained the economy of the town. The Musselshell Valley Historical Museum captures the coal history as well as fossils and Indian artifacts.
From Hell to Breakfast in Old Montana, by Leland Blanchard, tells the story of pioneers who lived and worked in Roundup in the early 1900s.
Roundup is a hub in Amazon.com's supply chain with a growing industry of prep centers, or businesses that specialize in packing goods to meet the requirements of Amazon's highly automated warehouses.
As of the census of 2010, there were 1,788 people, 814 households, and 445 families residing in the city.