It heads southeasterly, climbing slightly to the edge of the Oquirrh Mountains, and then curving between the south end of the range and the Deseret Chemical Depot.

The route proceeds east on Main Street, crossing Interstate 15 before coming to its eastern terminus at US-89.

The remainder of the route followed its present alignment to SR-36, replacing the portions of SR-202 and SR-180 that lay outside the canyons in the Rush Valley.

Finally, a connection from the Deseret Chemical Depot north to SR-73 near its west end, constructed with federal aid in 1942,[10] was numbered State Route 198.

This completely removed Mercur from the state highway system, but Fairfield was kept by moving SR-73 to its current alignment through that community.

[3] In 2011, in conjunction with the building of the Pioneer Crossing (SR-145) extension, the segment on Crossroads Boulevard between SR-68 and 850 East in Lehi was removed from the state highway system, which made SR-73 a discontinuous route.