Spanning 133.8 miles across the heart of the Mountain West, the drive from Thermopolis to Casper is a straightforward journey that typically takes about 2 hours and 39 minutes. Because the trip is relatively short, it functions perfectly as a single-day excursion, allowing you to reach your destination without needing an overnight stop. You should budget approximately $21 for fuel to complete the trek. The route primarily utilizes West US Highway 20-26, US 20, and East 2nd Street to navigate between these two Wyoming hubs. Whether you are traveling for business or leisure, this path offers a reliable connection through the region's rugged landscape.
Trip Pace
Same-day drive is realistic
A same-day return is realistic if you keep stops short.
Break Rhythm
1 planned break
A short stop every 2 to 3 hours is enough for this drive.
Midpoint
66.9 miles from Thermopolis, WY
A natural place for your longest stop of the day
, about 1h 19m into the drive
.
Main Roads
Road
Distance
Duration
West US Highway 20-26
60.7 mi
1h 8m
US 20
34 mi
40m
East 2nd Street
33.1 mi
37m
Bryan Stock Trail
1.1 mi
2m
East Sunlight Drive
0.9 mi
3m
Shoshoni Street
0.9 mi
2m
South 6th Street
0.5 mi
1m
North Sunlight Drive
—
—
Some road-level metrics are being recalculated.
Longest stretch:
West US Highway 20-26
— 60.7 mi, about 1h 8m
Turn-by-Turn Driving Directions
Step-by-step road directions between Thermopolis, WY and Casper, WY.
1
Start on US 20; WY 789
0.5 mi·1 min·South 6th Street
Use the straight / left / right lanes.
2
Turn right onto US 20; WY 789
0.9 mi·2 min·Shoshoni Street
Use the left / slight right lanes.
3
Continue on US 20; WY 789
31 mi·36 min·US 20; WY 789
Use the straight / right lanes.
4
Turn left onto US 20; US 26
33 mi·37 min·East 2nd Street
5
Continue on US 20; US 26
61 mi·1 hr 8 min·West US Highway 20-26
6
Turn left onto US 20; US 26
2.7 mi·3 min·US 20; US 26
7
Take the exit
2.5 mi·3 min
8
Take the exit onto US 20; US 26; US 87
0.3 mi·41 sec·US 20; US 26; US 87
Toward US 20 East, US 26 East, US 87 South: North Beverly Street, Bryan Stock Trail
9
At end of road, turn left onto I 25 Business
1.1 mi·2 min·Bryan Stock Trail
10
Turn left onto East Sunlight Drive
0.9 mi·3 min·East Sunlight Drive
11
Arrive at destination
North Sunlight Drive
Trip Plan
Given the manageable duration of the trip, you have plenty of flexibility regarding your departure time, though planning for at least one stop is recommended to break up the drive. Keep an eye on your fuel gauge before setting out, as the $21 cost estimate can fluctuate based on local prices along the route. Since you are covering over 130 miles, try to time your transit to avoid peak traffic hours when entering Casper on East 2nd Street. Because this is a highway-heavy route, ensure your vehicle is prepared for consistent speeds over the 60.7-mile stretch of West US Highway 20-26. Taking a quick breather mid-trip will keep you refreshed for the final approach into the city.
Morning Departure
Leave by 9 AM and you'll arrive before lunch.
Evening Departure
Even a 4 PM departure gets you there before dark in summer.
You can normally do this drive in one day.
Plan roughly 1 meaningful break for fuel, food, and rest.
The halfway point lands around 66.9 miles from Thermopolis, WY, or about 1h 19m into the drive.
The longest continuous stretch on this route runs about 60.7 miles.
This is a comfortable same-day trip.
Departure
Before you leave
Start with fuel, water, and navigation already sorted so the first hour feels easy.
First stop
Around 29 miles or 36m in
Use this first pause for coffee, a restroom break, and a quick traffic check ahead.
Halfway reset
Around 66.9 miles or 1h 19m in
This is the best place for your longest stop, a real meal, and a full fuel check.
Final approach
Final hour starts around 2h 7m
Traffic, exits, and arrival timing usually matter more near Casper, WY than in the middle of the route.
Before You Leave
+
Open the route before leaving Thermopolis, WY so your first major turns are already loaded.
+
Leave with enough water and a charging cable within reach, not packed away.
+
Check your fuel range against the first long segment, especially if you are starting outside city service areas.
Day 1
Settle into the route from Thermopolis, WY
This is one driving day of about 133.8 miles and 2h 39m.
Your first comfortable stop window is around 29 miles from Thermopolis, WY.
This route can stay practical as a one-day drive if traffic stays reasonable.
Plan about 1 real break rather than only quick fuel stops.
The longest stretch is on West US Highway 20-26 for about 60.7 miles.
Where to Stop
Rest stops, refuel points, and overnight suggestions along this route.
Place data sourced from public business listings. Hours and availability may vary.
Heads-up: tricky spots
5 of 8
5 decision points cluster between mile 0 and 131.7 — GPS handles the exact turns, but know they're coming. Your lane choice matters more than the turn itself.
4
0 mi into trip|~0m in|US 20; WY 789 / South 6th Street
Depart onto US 20; WY 789 / South 6th Street
Lane positioning matters here
Use the straight / left / right lanes.
4
0.5 mi into trip|~1m in|US 20; WY 789 / Shoshoni Street
Turn right onto US 20; WY 789 / Shoshoni Street
Lane positioning matters here
Use the left / slight right lanes.
4
128.9 mi into trip|~2h 29m in
Take the exit
Exit ramp - move to the correct lane early
5
131.4 mi into trip|~2h 33m in|US 20; US 26; US 87
Take the exit onto US 20; US 26; US 87 toward US 20 East, US 26 East, US 87 South: North Beverly Street, Bryan Stock Trail
Exit ramp - move to the correct lane early. Multiple destination signs - pick the right one
Toward US 20 East, US 26 East, US 87 South: Nor...
4
131.7 mi into trip|~2h 33m in|I 25 Business / Bryan Stock Trail
At end of road, turn left onto I 25 Business / Bryan Stock Trail
Navigation decision point
Fuel & Cost
Regular Gas
$21.20 one way
$42.41 round trip
$4.03/gal25.4 MPG avg47 kg CO2
Fuel Type
$/gal
One Way
Round Trip
midgrade
$4.22
$22.22
$44.45
premium
$4.53
$23.87
$47.74
diesel
$5.61
$29.54
$59.08
No toll roads detected on this route.
Estimated Trip Cost (one way, 1 person)
Fuel
$21
Meals
$25–$50
Total
$46–$71
Rough estimate based on US averages. Hotel $80–$140/night, meals $25–$50/day.
Estimated CO2 emission: 46.8 kg one way.
Prices: EIA weekly data, 2026-04-13.
Driving Electric?
About $14 in charging
· 0 stops
· 66% less CO2
Vehicle Type
kWh
Stops
DC Fast
Home Charge
Average EV
40.1
0
$14.05
$6.42
Efficient EV
33.5
0
$11.71
$5.35
EV Truck/SUV
53.5
0
$18.73
$8.56
Gas CO2
47 kg
EV CO2
16 kg (66% less)
This trip is well within single-charge range for most EVs. No charging stops needed if you start fully charged.
DC fast charging avg $0.35/kWh. Home charging avg $0.16/kWh. US grid CO2: 0.39 kg/kWh.
Travel Intel
Current conditions at both ends of the drive.
Forecast as of Apr 16, 2026
Origin
Thermopolis, WY
Night
in Thermopolis on Saturday
Local time
10:20 PM
MDT
Current temp
38°F
Unavailable
Live forecast
Destination
Casper, WY
Night
in Casper on Saturday
Local time
10:20 PM
MDT
Current temp
44°F
Unavailable
Live forecast
Seasonal Notes
Summer travel usually means heavier construction, hotter rest stops, and busier weekend traffic around major cities.
Winter travel shortens daylight, so a route that looks manageable on paper can feel much longer after dark.
Holiday weekends tend to make both departure and arrival windows slower than the raw route time suggests.
Time zone
Same local time
Origin and destination are on the same clock, so arrival timing is easier to judge at a glance.
Temperature spread
6 degrees warmer at arrival
A meaningful temperature swing is a good cue to rethink layers, water, and how soon you want to arrive.
Road read
2h 39m on the road
Use the two city cards together: check the sky where you start, then compare it with the local time and temperature at arrival.
Weather data from the National Weather Service. Conditions may change; check closer to your travel date.
More Details
What kind of drive is this?
This highway-focused drive is defined by a consistent pace, with 71% of the journey spent on major thoroughfares. You will encounter a longest uninterrupted stretch of 60.7 miles on West US Highway 20-26, which allows for steady progress through the terrain. The road personality shifts from open highway cruising to local navigation as you approach the city limits of Casper. Expect a functional, direct experience behind the wheel that prioritizes efficiency over technical, winding backroads. It is a classic Wyoming drive where the open road dictates the rhythm of your travel.
71% highway — fuel and pacing are the main things to plan.
11 navigation steps total — most of the decisions cluster near the start and finish.
Longest single stretch: 60.7 mi on West US Highway 20-26.
How Hard Is This Drive?
3/10
This is a straightforward highway drive that stays mostly on West US Highway 20-26 and US 20. There are only a few real navigation decisions along the way. The trickiest moment comes early in the drive near US 20; WY 789 / South 6th Street.
Driving Effort3/10
Easy - simple navigation with a manageable amount of wheel time
Balances navigation complexity with total wheel time.
This is a straightforward 2h 39m drive. You will face about 8 decision points, but nothing that requires special attention if you follow navigation.
Where does it get tricky?
The main spots that need attention: near the start (US 20; WY 789 / South 6th Street): Lane positioning matters here; at 0.5 miles (US 20; WY 789 / Shoshoni Street): Lane positioning matters here; at 128.9 miles: Exit ramp - move to the correct lane early.
Who Is This Route For?
Weekend Trip
Doable as a same-day drive at 2h 39m. Total distance: 133.8 miles.
Family Friendly
Moderate complexity with 1 natural rest stops along the way.
The longest stretch is about 60.7 miles on West US Highway 20-26. The full list of main roads is in the Roads section above.
Yes, with realistic expectations. Build in a stop roughly every 2 hours, have snacks and activities ready, and check the Nearby Places tabs for kid-friendly stops along the way.
Mostly yes along the main roads, but rural stretches through WY can have sparse or no coverage. Before you leave, download offline Google Maps or Apple Maps for the route, and consider downloading music or podcasts instead of streaming. If you depend on data for navigation, keep a paper backup of the turn-by-turn directions.
The main spots that need attention: near the start (US 20; WY 789 / South 6th Street): Lane positioning matters here; at 0.5 miles (US 20; WY 789 / Shoshoni Street): Lane positioning matters here; at 128.9 miles: Exit ramp - move to the correct lane early.
Yes. A round trip is manageable in a single day if you plan a break at Casper, WY before heading back.
