Question: Which  county located in the U.S. state of Montana is Brockton  a town in

Context paragraphs:
Flathead County, Montana: Flathead County is a county located in the U.S. state of Montana.  As of the 2010 census, the population was 90,928, making it the fourth-most populous county in Montana.  Its county seat is Kalispell.  The numerical designation for Flathead County (used in the issuance of license plates) is 7.  It is south from the Canada–US border of British Columbia.

Treasure County, Montana: Treasure County is a county located in the U.S. state of Montana.  As of the 2010 census, the population was 718, making it the second-least populous county in Montana.  Its county seat is Hysham.  The county was founded in 1919.

Carter County, Montana: Carter County is a county located in the U.S. state of Montana.  As of the 2010 census, the population was 1,160, making it the fifth-least populous county in Montana.  The county seat is Ekalaka.

Chouteau County, Montana: Chouteau County is a county located in the North-Central region of the U.S. state of Montana.  As of the 2010 census, the population was 5,813.  Its county seat is Fort Benton.  The county was established in 1865 as one of the original nine counties of Montana, and named in 1882 after Pierre Chouteau, Jr., a fur trader who established a trading post that became Fort Benton, which was once an important port on the Missouri River.

Toole County, Montana: Toole County is a county located in the northern portion of the U.S. state of Montana.  As of the 2010 census, the population was 5,324.  Its county seat is Shelby.  The county was established in 1914 from parts of Hill County and Teton County and was named after Joseph Toole, the first and fourth governor of Montana.  Its northern boundary is the Canada–United States border south of Alberta.

Cascade County, Montana: Cascade County ("cascade" means "waterfall" in French) is a county located in the U.S. state of Montana.  As of the 2010 census, the population was 81,327, making it the fifth-most populous county in Montana.  Its county seat is Great Falls.

Phillips County, Montana: Phillips County is a county located in the U.S. state of Montana.  As of the 2010 census, the population was 4,253.  Its county seat is Malta.  Before February 5, 1915, Phillips County was part of Blaine County, Montana, and before 1912 both were part of Chouteau County, Montana.  It was named in honor of rancher and state senator Benjamin D. Phillips.

Brockton, Montana: Brockton is a town in Roosevelt County, Montana, United States.  The population was 255 at the 2010 census.

Petroleum County, Montana: Petroleum County is a county located in the U.S. state of Montana.  As of the 2010 census, the population was 494, making it the least populous county in Montana and the seventh-least populous in the United States.  Its county seat is Winnett.  The Montana Legislature approved the formation of the county by separating it from Fergus County; Petroleum County was thus created on February 25, 1925, as the last of Montana's 56 counties.

Roosevelt County, Montana: Roosevelt County is a county located in the U.S. state of Montana.  As of the 2010 census, the population was 10,425.  Its county seat is Wolf Point.  Roosevelt County was created by the Montana Legislature in 1919 from Sheridan County.  The name honors former president Theodore Roosevelt, who had died shortly before the county was formed.

Supporting paragraphs: Brockton, Montana Roosevelt County, Montana
Answer: Roosevelt County