Jefferson County, Montana

Jefferson County
Jefferson County
County
	Jefferson County Courthouse in Boulder
	Location within the U.S. state of Montana
	Montana's location within the U.S.
	Coordinates: 46°11′N 112°07′W / 46.18°N 112.11°W
Country	United States
State	Montana
Founded	February 2, 1865
Named for	Thomas Jefferson
Seat	Boulder
Largest town	Clancy
Area
• Total	1,659 sq mi (4,300 km2)
• Land	1,656 sq mi (4,290 km2)
• Water	2.6 sq mi (7 km2) 0.2%
Population (2020)
• Total	12,085
• Estimate (2022)	12,826
• Density	7/sq mi (3/km2)
Time zone	UTC−7 (Mountain)
• Summer (DST)	UTC−6 (MDT)
Congressional district	2nd
Website	www.jeffersoncounty-mt.gov
	Montana county number 51;

Jefferson County is a county in Montana, United States. As of the 2020 census, the population was 12,085.^[2] Its county seat is Boulder.^[3] The county was created in 1865^[4] and named for President Thomas Jefferson.^[5]

Jefferson County is part of the Helena, MT Micropolitan Statistical Area.

^ "Montana County Formation Table". genealogytrails.com. Retrieved April 3, 2018.
^ "State & County QuickFacts". United States Census Bureau. Retrieved May 8, 2023.
^ "Find a County". National Association of Counties. Archived from the original on May 31, 2011. Retrieved June 7, 2011.
^ "Montana Place Names Companion". Montana Place Names From Alzada to Zortman. Montana Historical Society Research Center. Retrieved December 1, 2014.
^ Gannett, Henry (1905). The Origin of Certain Place Names in the United States. Govt. Print. Off. p. 168.