The 1940 Idaho gubernatorial election was held on November 5. Democratic nominee Chase Clark defeated incumbent Republican C. A. Bottolfsen with 50.48% of the vote.
The next election in 1942 was a rematch, also close, with different results.
Primary elections.
Primary elections were held on August 13, 1940.
General election.
Results.
! scope="col" colspan="2" style="width: 130px"|Party
! scope="col" style="width: 17em"|Candidate
! scope="col" style="width: 5em"|Votes
! scope="col" style="width: 3.5em"|%
! scope="col" style="width: 3.5em"| ;templatestyles src="Template:Tooltip/styles.css" / ;±%
! colspan="3" style="text-align: right; margin-right: 0.5em" | Majority
! colspan="3" style="text-align: right; margin-right: 0.5em" scope=row | Turnout
! style="text-align:right;" | Swing
References.
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