Utah State Route 20 is a 20.492 mile State Highway which connects Interstate 15 in Iron County east to US Route 89 in Garfield County. Utah State Route 20 ascends a gap between the Markagunt Plateau and Tushar Mountains which is aligned partially over the historic route of the Old Spanish Trail. Utah State Route 20 is popular as a freight corridor and as a reliable means for traffic to approach Bryce Canyon National Park.
Part 1; the history of Utah State Route 20
As noted in the intro the corridor of Utah State Route 20 ("UT 20") is closely aligned with the Old Spanish Trail. The Old Spanish Trail was a corridor established by Spanish explorers during the Las Californias period of the 18th Century between Santa Fe and Los Angeles. The Old Spanish Trail progressing towards the American Period became well established and was largely incorporated into emigrant roads. The Spanish Trail passed through the gap in the Markagunt Plateau and Tushar Mountains west from modern US Route 89 via what is now; UT 20, Upper Bear Valley Road and Little Creek Canyon Road to UT 271 (former US Route 91) near Paragonah. This alignment is cited as part of the official Old Spanish Trail touring route by the National Park Service.
The route of the Old Spanish Trail through the gap between the Markagunt Plateau and Tushar Mountains was adopted as a Utah State Highway in 1917. This State Highway was assigned as UT 20 in 1927 which can be seen aligned between US Route 89 west to US Route 91 in Paragonah on the 1931 Clason's Road Map of Utah.
The first UT 90 was commissioned by the State of Utah in 1935 as a new highway connecting from UT 20 in Little Bear Valley northwest to US Route 91. The original UT 90 appears for the first time on the 1939 Rand McNally Map of Nevada-Utah.
The original UT 90 was decommissioned in 1947 as it was consolidated into a realigned UT 20. Following the realignment of UT 20 what had been the original alignment on Upper Bear Valley Road and Little Creek Canyon Road was relinquished from the State Highway System. The realignment of UT 20 in 1947 forms the basis for the modern highway and can be seen on the 1950 Shell Highway Map of Utah.
Part 2; a drive on Utah State Route 20
UT 20 eastbound begins in Iron County from Interstate 15 Exit 95.