The 9-year-old Great Pyrenees was first elected as a write-in candidate in the small town of Cormorant, Minnesota, in 2014, beating out his the human competition.
"Three years ago, it happened by accident; it was a write-in vote. You pay a dollar and you can vote," said David Rick, Duke's owner.
"How (did) you feel after that election?" a reporter asked Richard Sherbrook, a former mayoral candidate who ran against Duke.
"Well, it was really depressing at first, but I'm getting over it real good," he told TV3. Sherbook later said that he would "back the dog 100 percent," and that Duke is "a sportsman and he likes to hunt -- he'll really protect the town."
Duke's honorary position in a town of about 1,000 people isn't completely unprecedented in the state. Another small town in the state -- Dorset, Minnesota -- has had some unconventional mayors as well: preschool-age children.
Rick told WDAY that Duke won the election in a landslide.
"Everybody voted for Duke, except for one vote for his girlfriend, Lassie," he said.
"I don't know who would run against him because he's done such great things for the community," said Cormorant resident Karen Nelson, who added that the dog stays " pretty busy working at the farm."