The Milwaukee Road, officially known as the Chicago, Milwaukee, St. Paul and Pacific Railroad (CMSP&P RR), was a Class I railroad that operated across the Midwest and northwestern United States from its founding in 1847 until its merger with the Soo Line Railroad in 1985–1986. Over its history, the company underwent several name changes and periods of bankruptcy. Although it no longer exists as a separate entity, its legacy is preserved through landmarks such as the historic Milwaukee Road Depot in Minneapolis, Minnesota, and through preserved equipment like the Milwaukee Road 261 steam locomotive.

Originally incorporated as the Milwaukee and Waukesha Railroad in 1847, the company soon changed its name to the Milwaukee and Mississippi Railroad. Its first rail line, connecting Milwaukee and Wauwatosa, Wisconsin, opened in 1850, with passenger service beginning on February 25, 1851. The name was changed in 1874 to the Chicago, Milwaukee and St. Paul Railroad, and by 1887, it had expanded lines through Wisconsin, Minnesota, Iowa, South Dakota, and Michigan’s Upper Peninsula.