The western portion follows the general corridor used by the
California Trail, as well as the
First transcontinental railroad, completed in 1869. This portion of the railroad was bypassed with the construction of the
Lucin Cutoff across the
Great Salt Lake. Later the road would be part of the
Midland Trail, and it was added to the state highway system in 1912. The entire roadway from
Nevada via
Snowville to
Tremonton remained a state highway through 1925, 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. The road to the Nevada state line, where it continued as
SR 30, was restored in 1931 as
State Route 70. The central portion, between
Tremonton and
Logan, was added to the state highway system in 1931 as
SR-102 (Tremonton to
Deweyville) and
SR-69 (Deweyville to Logan). From 1938 until the mid-1950s, the SR-69 portion was marked as
US-89, which, instead of
overlapping
US-91, followed the longer all-weather route from
Brigham City into the
Cache Valley. Various cutoffs were formed at the west end:
State Route 154 came first in 1933, connecting
SR-41 (now
SR-82) in
Garland with SR-69 near
Collinston via Garland Road.
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, only to be given back to the county in 1953. The roadway from Riverside east to SR-154 was brought back into the state highway system in 1962 as part of
SR-84, which was to end at a junction with the proposed
I-15 between Riverside and Collinston. When SR-154 was deleted in 1969, the SR-84 designation was extended east to Collinston, replacing part of that route. 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. For continuity,
SR-13 (which had replaced SR-84 in 1977) was cut back to Riverside, with the Riverside-Collinston portion also becoming SR-129. In 1969 the piece east of
Bothwell Junction became part of a western extension of SR-102. The portion east of
Garden City was added to the state highway system in 1910 (Garden City to
Sage Creek Junction) and 1915 (Sage Creek Junction to Wyoming). The former became part of
SR-3 in the 1920s, and in 1927 the legislature added the latter as a branch of that route, only to split it off as
State Route 51 in 1931. SR-3 was renumbered to
SR-16 in 1962. • SR-70, Nevada to
Curlew Junction •
US-30S, Curlew Junction to
Snowville •
I-80N, Snowville to
Bothwell Junction (now
I-84) •
SR-102, Bothwell Junction to
Deweyville •
SR-69, Deweyville to
Logan •
US-89/
US-91 in Logan • US-89, Logan to
Garden City •
SR-16, Garden City to
Sage Creek Junction • SR-51, Sage Creek Junction to Wyoming 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). No signage changes were required except for the removal of the rectangular signs below the SR-30 shields. 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. ==Major intersections==