Lincoln County is a county located in the U.S. state of Montana. As of the 2020 census, the population was 19,677. Its county seat is Libby. The county was founded in 1909 and named for President Abraham Lincoln. The county lies on Montana's north border and thus shares the US-Canadian border with the Canadian province of British Columbia.

Libby is a city in northwestern Montana, United States and the county seat of Lincoln County. The population was 2,775 at the 2020 census.