The Milwaukee Road Historic District is a historic district encompassing the Milwaukee Road railway depot and facilities in Harlowton, Montana. The depot was built in 1908, and rail service to Harlowton began the same year. In 1916, the facilities at Harlowton gained international renown when the Milwaukee Road made the depot the eastern endpoint of an electrified section of rail which extended to Avery, Idaho. The electrified section was the longest stretch of electric railroad in the United States; Thomas Edison described the railroad as an "unmatched technical marvel". Harlowton was also an important division point for the railroad, and its facilities include the railroad's standardized Class A passenger station and a rare example of an intact roundhouse. In addition to its importance to the railroad, the Harlowton rail facilities were also important to the local economy, as the railroad was the city's largest employer.