After about 2 miles (3.2 km), the route starts to "stairstep", alternately going north and east through Penrose and Thatcher, before settling on an easterly direction through Bothwell.

In 1969, the route was extended westward through Tremonton to SR-83 east of Lampo Junction (this stretch of road was formerly part of SR-3).

Instead, the old route numbers were kept and marked on small, rectangular signs below the SR-30 shields.

[2][4] In the 1977 renumbering, the legislative description of this new route was changed to SR-30, resulting in SR-102's eastern terminus being moved to I-84.

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 being extended back to Deweyville.