The western segment is a historic corridor paralleling the pre-Lucin Cutoff routing of the First transcontinental railroad.

SR-30 starts at the Nevada state line connecting with SR 233 and loosely follows the original route of the First transcontinental railroad around the north shore of the Great Salt Lake.

The segment between 3200 West in Cache County and the US-89/US-91 junction in Logan is part of the National Highway System.

The eastern section branches off from US-89 at Garden City and follows the south shore of Bear Lake to Laketown.

[4][5][6] The entire roadway from Nevada via Snowville to Tremonton remained a state highway through 1925,[7] but in 1927 the portion west of Curlew Junction was dropped, with the remainder serving as part of U.S. Route 30S (US-30S), designated in 1926, which continued northwest to Idaho.

[15] State Route 85 was built in 1940 as a federal aid project, connecting SR-41 (now SR-13) in Riverside with SR-154, and numbered by the legislature in 1945,[16] only to be given back to the county in 1953.

[18] By 1982, proposed I-15 had been moved west to its current alignment north of Tremonton, and a new State Route 129 was created to connect it with Riverside.

SR-30 was marked along the following routes:[26] In the 1977 renumbering, the legislative designation was changed to SR-30, except on the portions that were signed as U.S. or Interstate Highways (hence the gaps at I-84 and US-89).

In 1989, the commission resolved that, once I-15 was completed north of Tremonton, SR-30 would be rerouted to replace SR-129, with SR-102 and SR-69 (now SR-38) being extended back to Deweyville and Collinston.