The 1966 Idaho gubernatorial election was held on November 8. Republican nominee Don Samuelson defeated Democratic nominee Cecil Andrus with 41.4% of the vote in a four-way race (two independents).[1]
In early August, three-term incumbent Robert E. Smylie, the dean of American governors, was soundly defeated in the Republican primary by Samuelson.[2] Andrus was a close runner-up in the Democratic primary to Charles Herndon,[2] who was killed in a plane crash six weeks later in September.[3][4]
This was the sixth consecutive Republican victory for governor, but Democrats won the next six, with four by Andrus. The next gubernatorial election in 1970 was a rematch, with different results.