Rosemount is a city in Dakota County, Minnesota, United States, in the Twin Cities Metropolitan Area. The population was 21,874 at the 2010 census. Rosemount was established as a township in 1858 and incorporated as a city in 1972, encompassing the old village of Rosemount and Pine Bend. According to the city's website, there was some debate over whether to name the township Saratoga or Rosemount, with the latter finally being chosen to reflect the town's Irish heritage, and to remain in keeping with the name given to the post office a few years earlier. Rosemount is home to the Pine Bend Refinery, which is the largest oil refinery in Minnesota and the 14th-largest in the United States. Rosemount was also home to a military gunpowder plant in the 1940s called Gopher Ordnance Works. Now, all that remains are the walls.