Spanning 510 miles across the Mountain West, this journey from Lewiston to Ashton is a significant undertaking that requires careful planning. With a total drive time of 10 hours and 8 minutes, attempting this in a single day is exhausting, so I recommend splitting the trip over two days. You will primarily navigate via US 12, the Jeannette Rankin Memorial Highway, and US 287. Budgeting approximately $81 for fuel is a smart starting point for your trip calculations. Because this route stays entirely within Idaho, you will experience a consistent regional feel, though the distance makes it a serious commitment for any traveler.
Trip Pace
Best split across 2 days
Treat the return leg as its own travel day rather than an afterthought.
Break Rhythm
2 planned breaks
Plan on a short reset every 3 to 4 hours to stay fresh behind the wheel.
Midpoint
255 miles from Lewiston, ID
A natural place for your longest stop of the day
, about 5h 27m into the drive
.
Main Roads
Road
Distance
Duration
US 12
212.4 mi
4h 42m
Jeannette Rankin Memorial Highway
115.1 mi
1h 49m
US 287
68.5 mi
1h 18m
Idaho Medal of Honor Highway
41.7 mi
50m
I 15
33.9 mi
34m
MT 359
14.6 mi
17m
ID 87
9.1 mi
11m
MT 87
8.6 mi
12m
Longest stretch:
US 12
— 212.4 mi, about 4h 42m
Traffic on I-90
Hour-of-day weekday pattern from 8 FHWA count stations on your route.
Peak
3 PM
~339 veh/hr typical
· worst 471
Quietest
2 AM
~31 veh/hr
Peak-to-quiet ratio
10.9×
busier at peak than in the quiet hours
12a6anoon6p11p
Averaged across 52 weeks of 2023 FHWA Travel Monitoring Analysis System data. Weekday hours only (Mon–Fri).
Turn-by-Turn Driving Directions
Step-by-step road directions between Lewiston, ID and Ashton, ID.
1
Start on this road
105 ft·9 sec·this road
2
Turn right onto Idaho Street
0.7 mi·1 min·Idaho Street
3
Turn right onto 19th Street
288 ft·18 sec·19th Street
4
Turn left onto 7th Avenue
0.1 mi·30 sec·7th Avenue
5
At end of road, turn left onto 21st Street
339 ft·10 sec·21st Street
6
Continue on US 12
1.0 mi·2 min·US 12
7
Keep slight right at fork onto US 12
7.4 mi·8 min·US 12
Toward US 95 South: Missoula, BoiseUse the straight lane.
8
Take the exit onto US 12
164 mi·3 hr 42 min·US 12
Toward US 12 East
9
Continue on US 12
33 mi·39 min·US 12
10
Continue on US 12; US 93
7.0 mi·9 min·US 12; US 93
11
Continue on Brooks Street
3.3 mi·4 min·Brooks Street
Use the straight / right lanes.
12
Continue on US 12
356 ft·16 sec·South Higgins Avenue
Use the left lane.
13
Turn right onto US 12
0.4 mi·36 sec·South 6th Street East
14
Turn left onto Arthur Avenue
0.2 mi·13 sec·Arthur Avenue
15
Continue on US 12
0.2 mi·15 sec·Madison Street
16
Take the exit onto US 12
0.2 mi·26 sec·US 12
17
Turn left onto I 90 Bus; US 12
435 ft·5 sec·Van Buren Street
18
Take the exit onto I 90 Business; US 12
0.2 mi·29 sec·I 90 Business; US 12
19
Merge onto I 90; US 12; MT 200
115 mi·1 hr 49 min·Jeannette Rankin Memorial Highway
20
Keep slight right at fork onto I 15; I 90
34 mi·34 min·I 15; I 90
Use the straight / slight right lanes.
21
Take the exit
0.3 mi·38 sec
Toward MT 359: Cardwell, Boulder
22
Turn right onto MT 2
152 ft·3 sec·MT 2
23
Continue on MT 359
15 mi·17 min·MT 359
24
At end of road, turn right onto US 287
28 mi·33 min·US 287
25
At end of road, turn left onto US 287
40 mi·45 min·US 287
26
Turn right onto MT 87
8.6 mi·12 min·MT 87
27
Continue on ID 87
9.1 mi·11 min·ID 87
28
At end of road, turn right onto US 20
42 mi·50 min·Idaho Medal of Honor Highway
29
Turn left onto ID-47
0.4 mi·40 sec·Main Street
30
Arrive at destination
ID-47
Trip Plan
To manage the 10-hour duration effectively, plan for at least two intentional stops to stretch your legs and refresh. Since the longest stretch is over 200 miles, prioritize refueling whenever you see a station, rather than waiting until your tank is near empty. I suggest departing early in the morning to maximize daylight, especially if you opt for a two-day itinerary to break up the mileage. Always keep an eye on your fuel gauge during that 212.4-mile stretch on US 12, as finding reliable service can be more challenging in remote sections. Taking the time to pace yourself will make the 510-mile distance feel much more manageable.
Morning Departure
Start early — leave by 6-7 AM to arrive at a reasonable hour.
Evening Departure
This is a long drive — plan for a morning departure or consider splitting it into two days.
This drive is better paced as a 2-day trip.
Plan roughly 2 meaningful breaks for fuel, food, and rest.
The halfway point lands around 255 miles from Lewiston, ID, or about 5h 27m into the drive.
The longest continuous stretch on this route runs about 212.4 miles.
Consider an overnight stop or starting very early.
Departure
Before you leave
Start with fuel, water, and navigation already sorted so the first hour feels easy.
First stop
Around 112 miles or 2h 33m in
Use this first pause for coffee, a restroom break, and a quick traffic check ahead.
Halfway reset
Around 255 miles or 5h 27m in
This is the best place for your longest stop, a real meal, and a full fuel check.
Overnight split
Day 1 wrap after about 255 miles or 5h 27m
Stop before fatigue turns the last few hours into a grind. You want day two to start fresh, not just resumed.
Final approach
Final hour starts around 8h 52m
Traffic, exits, and arrival timing usually matter more near Ashton, ID than in the middle of the route.
Before You Leave
+
Open the route before leaving Lewiston, ID 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.
+
Pick one backup stop option before the midpoint in case traffic changes your pacing.
+
Treat this as a 2-day road trip and book the overnight stop before the busiest arrival window.
Day 1
Settle into the route from Lewiston, ID
Aim for roughly 255 miles and 5.1 hours of wheel time on this day.
Day 2
Finish the approach into Ashton, ID
Aim for roughly 255 miles and 5.1 hours of wheel time on this day.
Your first comfortable stop window is around 112 miles from Lewiston, ID.
This route usually feels better as a 2-day drive than as one long push.
Plan about 2 real breaks rather than only quick fuel stops.
The longest stretch is on US 12 for about 212.4 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 20
5 decision points cluster between mile 0.7 and 366.8 — GPS handles the exact turns, but know they're coming. Your lane choice matters more than the turn itself.
5
0.7 mi into trip|~2m in|7th Avenue
Turn left onto 7th Avenue
Navigation decision point
5
0.9 mi into trip|~2m in|21st Street
At end of road, turn left onto 21st Street
Navigation decision point
8
1.9 mi into trip|~4m in|US 12
Keep slight right at fork onto US 12 toward US 95 South: Missoula, Boise
Highway fork - watch signs carefully. Lane positioning matters here. Multiple destination signs - pick the right one
Use the straight lane.
Toward US 95 South: Missoula, Boise
6
332.9 mi into trip|~6h 41m in|I 15; I 90
Keep slight right at fork onto I 15; I 90
Highway fork - watch signs carefully. Lane positioning matters here
Use the straight / slight right lanes.
5
366.8 mi into trip|~7h 16m in
Take the exit toward MT 359: Cardwell, Boulder
Exit ramp - move to the correct lane early. Multiple destination signs - pick the right one
Toward MT 359: Cardwell, Boulder
Fuel & Cost
Regular Gas
$89.65 one way
$179.30 round trip
$4.47/gal25.4 MPG avg178 kg CO2
Fuel Type
$/gal
One Way
Round Trip
midgrade
$4.67
$93.75
$187.50
premium
$4.99
$100.19
$200.39
diesel
$5.35
$107.42
$214.84
No toll roads detected on this route.
Estimated Trip Cost (one way, 1 person)
Fuel
$90
Hotel (1n)
$80–$140
Meals
$50–$100
Total
$220–$330
Rough estimate based on US averages. Hotel $80–$140/night, meals $25–$50/day.
Estimated CO2 emission: 178.4 kg one way.
Prices: EIA weekly data, 2026-06-01.
Driving Electric?
About $54 in charging
· 1 stop
· 66% less CO2
Vehicle Type
kWh
Stops
DC Fast
Home Charge
Average EV
153
1
$53.55
$24.48
Efficient EV
127.5
1
$44.63
$20.40
EV Truck/SUV
204
2
$71.40
$32.64
Gas CO2
178 kg
EV CO2
60 kg (66% less)
Plan for 1 charging stop. A 30-minute DC fast charge mid-route should be enough to complete the trip comfortably.
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 Jun 1, 2026
Origin
Lewiston, ID
Afternoon
in Lewiston on Wednesday
Local time
12:08 PM
PDT
Current temp
51°F
Mostly Cloudy
SE 2 mph1% chanceLive forecast
Destination
Ashton, ID
Afternoon
in Ashton on Wednesday
Local time
1:08 PM
MDT
Current temp
35°F
Mostly Clear
ENE 5 mph1% chanceLive 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.
For long drives, weather on day two can matter just as much as conditions at departure, so check the whole travel window rather than only the first day.
Time zone
1 hour later
The destination clock does not match departure time, so double-check hotel check-in windows and late arrival plans.
Temperature spread
16 degrees cooler at arrival
A meaningful temperature swing is a good cue to rethink layers, water, and how soon you want to arrive.
Road read
10h 8m on the road
This is long enough that the arrival forecast matters almost as much as departure conditions. Recheck both ends before you roll.
Weather data from the National Weather Service. Conditions may change; check closer to your travel date.
National Parks Near This Route
Worth a detour if your schedule allows.
Nez Perce National Historical Park
National Historical Park
Since time immemorial, the valleys, prairies, mountains, and plateaus of the inland northwest have been home to the nimíipuu (Nez Perce) people. Extremely resilient, they survived the settling of the...
8 mi from route
~20 min detour
Free
near mile 87.9
Park data from the National Park Service API. Alerts update every 2 hours.
More Details
What kind of drive is this?
Expect a mix of driving environments on this 510-mile trek, where highway driving accounts for 68% of the journey. The experience is defined by a significant 212.4-mile stretch on US 12, which serves as your longest uninterrupted segment. Transitioning between the various highways keeps the drive from feeling like a monotonous interstate grind, though the length requires sustained focus. As you progress through the Mountain West, the road character shifts, demanding that you stay alert during the longer, high-mileage portions of the drive.
68% highway — fuel and pacing are the main things to plan.
30 navigation steps total — most of the decisions cluster near the start and finish.
Longest single stretch: 212.4 mi on US 12.
How Hard Is This Drive?
6/10
At 10h 8m, this is a long-haul route where pacing matters more than any single turn. You will hit about 20 points where you need to pay attention to lane position or signs. The trickiest moment comes around 0.7 miles in near 7th Avenue.
Driving Effort6/10
Moderate - straightforward overall, but long enough or busy enough to require pacing
Balances navigation complexity with total wheel time.
This drive requires moderate attention. Across 510 miles you will encounter 20 spots where lane choice or exit timing matters. Not difficult for experienced highway drivers, but worth previewing the tricky sections before you go.
Where does it get tricky?
The main spots that need attention: at 0.7 miles (7th Avenue): Navigation decision point; at 0.9 miles (21st Street): Navigation decision point; at 1.9 miles (US 12): Highway fork - watch signs carefully. Lane positioning matters here. Multiple destination signs - pick the right one.
Elevation Profile
High-altitude sections with notable climbs
6,435 ft741 ft
Total Climb
7,565 ft
Total Descent
3,045 ft
Highest Point
6,435 ft
~473.5 mi in
Elevation Range
5,695 ft
Notable High Points
4,092 ft at ~182.1 miles+861 ft prominence
5,364 ft at ~327.8 miles+938 ft prominence
6,435 ft at ~473.5 miles+721 ft prominence
Towns Mentioned on Route Signs
Based on OSRM destination-sign hints, not a full list of every settlement the road passes.
On the drive from Lewiston, ID to Ashton, ID, road signs begin pointing toward Boulder along the way.
Boulder
366.8 mi in|~7h 16m
Detours Along the Way
Tagged by where each one fits in your drive — first break, midpoint, final stretch.
Lewiston is the county seat of and largest city in Nez Perce County, Idaho. It is the second largest city in the Idaho Panhandle region behind Coeur d'Alene. It sits across the river from Clarkston, Washington. In 2020, Lewiston was home to 34,000 people. Like Pocatello, Lewiston has a strong working-class heritage. Industries related to timber and logging pursuits have long been key to the city's economy. Because the Columbia and later the Snake River are navigable by some ocean-going vessels all the way to Lewiston, the city has the distinction of being Idaho's only port city, and the furthest inland port in the western United States.
Top landmarks
•Nave Apartments — apartment building in Lewiston, United States of America
Moderate complexity with 2 natural rest stops along the way.
Solo Traveler
10h 8m drive, plan rest stops for pacing.
Frequently Asked Questions
The longest stretch is about 212.4 miles on US 12. The full list of main roads is in the Roads section above.
Yes — a 2-day pace is more comfortable than one long haul. A sensible stopping point is after roughly 255 miles on day one.
Yes — we found about 11 rest areas or service plazas within a short detour of the route (from OpenStreetMap). See the Rest Stops tab under Nearby Places for locations and mile markers. Plan to stretch, use the bathroom, and top off fluids every 2–3 hours on longer drives.
It helps. This route has a higher-than-average number of complex decision points, which get harder in the dark. If the last hour of the trip is on surface roads or mountain grades, aim to arrive at Ashton, ID before sunset when you can. Check the Trip Plan for departure windows that land you in daylight.
Only with planning. This is a long drive for kids — consider splitting it into two days rather than pushing through. Plan at least 2 meaningful breaks. There are 11 rest areas along the route for bathroom stops.
Mostly yes along the main roads, but rural stretches through ID 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: at 0.7 miles (7th Avenue): Navigation decision point; at 0.9 miles (21st Street): Navigation decision point; at 1.9 miles (US 12): Highway fork - watch signs carefully. Lane positioning matters here. Multiple destination signs - pick the right one.
Yes — Nez Perce National Historical Park. See the National Parks section for detour distances and tips on detours.
Not recommended in a single day. At 10.1 hours each way, a round trip means 20.3 hours of driving — that is an unsafe level of fatigue for most drivers. Plan at least one night at Ashton, ID before the return drive.
