Churchill County was established in 1861, and was named for Fort Churchill (which is now in Lyon County), which was named for General Sylvester Churchill, a Mexican–American War hero who was Inspector General of the U.S. Army in 1861. Churchill County was not organized until 1864, and its first county seat was Bucklands (which is now in Lyon County). In 1864 the county seat was moved to La Plata;[3] in 1868 it was moved to Stillwater; and in 1904 it was settled in its present position, Fallon. In the 19th century there were several attempts to eliminate Churchill County because of its small population, but Assemblyman Lemuel Allen stopped it on all occasions including convincing the Governor to veto an 1875 bill after it had been passed by both houses.

Lying on the boundary between the northwest urban areas of Nevada and the conservative Mormon Great Basin, Churchill County has more in common with the latter region, being overwhelmingly Republican. It was one of three Nevada counties Barry Goldwater won in 1964, and since that time only Jimmy Carter in 1976 and Barack Obama in 2008 have passed so much as thirty percent of the county's ballots. The last time Churchill County voted for a Democratic presidential candidate was when it supported Franklin D. Roosevelt against Wendell Willkie in 1940.