In 1849, the provisional State of Deseret established seven counties: Davis, Iron, Sanpete, Salt Lake, Tooele, Utah, and Weber.

In the early 20th century, after Utah had become a state, the final two counties were created: Duchesne by gubernatorial proclamation (1913) and Daggett by popular vote (1917).

[7] The Utah Code (Title 17, Chapter 50, Part 5) divides the counties into six classes by population:[8] The county classes, for example, are used in the Utah legislature in crafting of legislation to distinguish between more urban and rural areas, such as important yet subtle distinctions in how revenue can be distributed.

[9] Under Utah Code (Title 17, Chapter 52a, Part 2), Utah counties are permitted to choose one of four forms of county government:[10] a three-member full-time commission; a five or seven member expanded commission; a three to nine member (odd-numbered) part-time council with a full-time elected county mayor or a three to nine member (odd-numbered) part-time council with a full-time manager appointed by the council.

In 1998, Salt Lake County residents approved adopting a nine-member council with elected mayor that began work in 2001.