US 20 in Wyoming

By | December 15, 2022


US 20
Get started West Yellowstone
End from Tassell
Length 524 mi
Length 843 km
  • Montana
  • Yellowstone National Park
  • Cody
  • Greybull
  • Worland
  • Thermopolis
  • Soshonia
  • Casper
  • Glenrock
  • Glenrock – Orin:
  • Orin
  • Lusk
  • Nebraska

According to allcitycodes, US 20 is a US Highway in the US state of Wyoming. The road forms a long east-west route across the state, running from the Montana border at West Yellowstone through Yellowstone National Park and Casper to the Nebraska border at Van Tassell. The route has significant double to quadruple numbering, with US 14, US 16, US 18, US 26, US 89, US 191, US 287 and Interstate 25. The road is 843 kilometers long, of which only 140 kilometers are not double numbered with other US Highways or Interstate Highways.

Travel directions

US 20 near Thermopolis.

US 20 in eastern Wyoming

East of West Yellowstone in Montana, US 20 in Montana crosses the Wyoming border and enters Yellowstone National Park. The road runs here at an altitude of about 2,100 meters and partly runs through a canyon. The road here is double numbered with US 191 and US 287. After 15 kilometers the US 89 is added, resulting in quadruple numbering. The road then goes a bit south and passes several geysers, such as Old Faithful. The road rises here to an altitude of about 2400 meters. At West Thumb, the road turns east and then triples with US 14 and US 16that start here. US 89, US 191, and US 287 continue south to Jackson and Rawlins.

You pass along the north side of Yellowstone Lake, over a plateau, the real mountain peaks are further away. You are here at an altitude of about 2,400 meters and the road then runs through an area with barely more trees to the east and after about 75 kilometers you leave the immense National Park. In addition, you will reach a maximum altitude of 2,600 meters. The road then continues through a much more mountainous area with steep ridges, with US 20 running through a deeper valley. The mountain peaks around reach up to 3,600 meters. The area is very dry, but not desert-like. One passes through the Shoshone National Forest. The Shoshone River flows parallel to the road, through a shallow canyon. One then passes through the small town of Cody, which is the largest town in the wider region. Here the US 14 Alternate turns to the northeast, which forms an alternative route further north. Both roads meet again 160 kilometers away. You then cross the windy and very desolate High Plains, at an altitude of about 1,500 meters. Almost nothing grows here and the road is very quiet. To the east you descend slowly, but you still have to go through the Bighorn Mountains. Just before the village of Greybull, theUS 310.

In Greybull there is a major intersection, US 14 continues straight towards Sheridan and US 16 and US 20 turn south and continue through the valley of the Bighorn River. Here are some signs of civilization in the form of limited agriculture and some villages. Despite the fact that US 20 is an east-west number, the road here goes more than 160 kilometers to the south. In Worland, the US strikes 16down east, toward Buffalo. The road runs south here at an altitude of about 1,200 meters, where the environment becomes more desolate, with hardly any agriculture left and mainly barren mountains and plains. One then passes through Thermopolis, a small town in Central Wyoming. The road then goes through the Wind River Canyon, a spectacular route between the rock walls. The road continues past Boysen Reservoir, a reservoir, and then reaches the village of Shoshoni, where the road turns east and begins double-numbering again, this time with US 26 coming west from Jackson.

The road then runs over a desolate barren plateau with few major differences in height. Places on the route are often no more than a few houses, sometimes not even inhabited. You pass Hells Half Acre, a wild area with jagged rocks. One then reaches the town of Casper, with 50,000 inhabitants the second largest city in Wyoming. The US 20 merges here with Interstate 25. Although I-25 is a north-south number, the road here runs east-west for 100 kilometers. Crossing the North Platte River here, US 20 and US 26 turn off again to form a parallel route a short distance from I-25. This continues until Glenrock, after which both numbers merge onto I-25, after which a double numbering to the east of 4 road numbers, I-25, US 20, US 26 and US 87. Just past Douglas, at the village of Orin the US 20 turns to the east and this is where the US 18 begins, so that immediately a double numbering towards the east is created.

The road runs here at an altitude of about 1,450 meters over the barren High Plains, along a railway line where sometimes kilometers of freight trains pass. You pass Lost Springs, a place with 1 resident. One does not pass places with inhabitants and the area is quite desolate. The largest town on the route is Lusk. Here US 18 merges with US 85. US 20 then forms the last 35 kilometers to the border with Nebraska and is not double-numbered here. At the village of Van Tassell, the road crosses the border into Nebraska, then US 20 in Nebraska continues to Chadron through the sparsely populated northern part of the state.


US 20/26 at Casper.

US 20 was one of the original US Highways of 1926 and started in Yellowstone National Park at the time. Originally, US 20 was the only east-west route through northwestern and central Wyoming, before a large number of double-numbering operations were established in the 1930s with the extensions of US 14, US 16, and US 18. route extended into Oregon, creating the entire route through Wyoming.

Between Casper and Thermopolis, US 20 replaced the historic Old Yellowstone Highway. It may have gone through what is now State Highway 120, which is a shorter route than US 20 between Thermopolis and Cody. This used to be the US 420. At the end of the 1940s, the road south of Thermopolis was moved due to the construction of the Boysen Reservoir, which was realized between 1947 and 1952. US 20 was then built eastward to Shoshoni.

Originally, US 20/26 passed through downtown Casper. At the time of construction of I-25, a North Casper bypass was also constructed, with 2×2 lanes. This is now the bypass route, while the old downtown route is now the business route of US 20/26.

Traffic intensities

Every day 1,400 to 2,200 vehicles drive between Yellowstone National Park and Cody, up to 13,000 vehicles in Cody itself, 700 to 1,300 vehicles between Cody and Greybull, 2,000 vehicles between Greybull and Worland, 2,200 vehicles to Thermopolis, 2,300 vehicles to Shoshone and 2,000 vehicles to Casper. There are also 2,000 vehicles on US 18/20 between I-25 and Lusk and 500 vehicles on the border with Nebraska.

US 20 in Wyoming