The drive from Idaho Falls, ID to Saint Maries, ID covers 491.8 miles and takes about 8h 19m behind the wheel.
It usually feels better as a 2-day road trip than as one long push.
The route leans on I 90, Veterans Memorial Highway, South Highway 3 for much of the mileage,
and the overall profile is mixed drive.
The longest uninterrupted segment is about 256.8 miles on I 90.
At current regular gas prices, budget about $77.93 one way before food or hotel costs.
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
245.9 miles from Idaho Falls, ID
A natural place for your longest stop of the day
, about 3h 58m into the drive
.
Who Is This Route For?
Family Friendly
Moderate complexity with 2 natural rest stops along the way.
Mixed drive route profile with national parks nearby.
Drive Character
The drive from Idaho Falls, ID to Saint Maries, ID covers 491.8 miles and takes about 8h 19m, using a mix of highways and local roads.
Expect a mix of faster highway mileage and slower local approaches near the beginning or end.
There are about 19 navigation steps in the underlying route data, so the final approach matters more than the middle miles.
I 90 is the longest continuous segment at about 256.8 miles.
How Hard Is This Drive?
This route mixes highway mileage with some local-road sections near the start or finish. There are only a few real navigation decisions along the way. The trickiest moment comes early in the drive near West Stone Run Lane.
Driving Effort4/10
Easy - simple navigation with a manageable amount of wheel time
Balances navigation complexity with total wheel time.
The route itself is not hard, but at 8h 19m, endurance matters. Plan breaks every 2-3 hours. The 13 decision points are all manageable with basic attention.
Where does it get tricky?
The main spots that need attention: near the start (West Stone Run Lane): Navigation decision point; at 0.1 miles (Stonebrook Lane): Navigation decision point; at 2.2 miles (South Utah Avenue): Roundabout - know your exit number before entering.
Critical Maneuvers
5 of 13 key points
These are the spots where you need to pay the most attention. Preview them before you drive.
5
0 mi into trip|~0m in|West Stone Run Lane
Turn right onto West Stone Run Lane
Navigation decision point
5
0.1 mi into trip|~0m in|Stonebrook Lane
Turn left onto Stonebrook Lane
Navigation decision point
6
2.2 mi into trip|~5m in|South Utah Avenue
Enter roundabout onto South Utah Avenue
Roundabout - know your exit number before entering
7
3 mi into trip|~6m in|I 15 BUS; US 20
Take the ramp onto I 15 BUS; US 20 toward I15 North: Roberts, Butte
Multiple destination signs - pick the right one
Exit 118
Toward I15 North: Roberts, Butte
5
458.8 mi into trip|~7h 30m in
Take the exit toward ID 3: Harrison, Rose Lake, Saint Maries
Exit ramp - move to the correct lane early. Multiple destination signs - pick the right one
Toward ID 3: Harrison, Rose Lake, Saint Maries
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 Idaho Falls, ID to Saint Maries, ID, road signs begin pointing toward Rose Lake along the way.
Rose Lake
458.8 mi in|~7h 30m
Main Roads
Road
Distance
Duration
I 90
256.8 mi
4h 16m
Veterans Memorial Highway
198.2 mi
3h 6m
South Highway 3
32.6 mi
48m
South Boulevard
1 mi
2m
South Utah Avenue
0.7 mi
1m
East 17th Street
0.6 mi
<1m
Pancheri Drive
0.4 mi
<1m
West Broadway Street
0.3 mi
<1m
Longest stretch:
I 90
— 256.8 mi, about 4h 16m
Turn-by-Turn Driving Directions
Step-by-step road directions between Idaho Falls, ID and Saint Maries, ID.
1
Start on Charleston Lane
152 ft·8 sec·Charleston Lane
2
Turn right onto West Stone Run Lane
241 ft·15 sec·West Stone Run Lane
3
Turn left onto Stonebrook Lane
466 ft·14 sec·Stonebrook Lane
4
Continue on South Boulevard
1.0 mi·2 min·South Boulevard
5
Turn left onto East 17th Street
0.6 mi·52 sec·East 17th Street
6
Continue on Pancheri Drive
0.4 mi·47 sec·Pancheri Drive
7
Turn right onto South Utah Avenue
0.1 mi·15 sec·South Utah Avenue
8
Enter roundabout onto South Utah Avenue
222 ft·4 sec·South Utah Avenue
9
Continue on South Utah Avenue
0.5 mi·58 sec·South Utah Avenue
10
Turn left onto I 15 BUS; US 20 BUS
0.3 mi·34 sec·West Broadway Street
11
Take the ramp onto I 15 BUS; US 20
0.2 mi·27 sec·I 15 BUS; US 20
Exit 118Toward I15 North: Roberts, Butte
12
Merge onto I 15; US 20
198 mi·3 hr 6 min·Veterans Memorial Highway
13
Take the exit
0.5 mi·1 min
Toward I 90 West: Missoula
14
Merge onto I 90
257 mi·4 hr 16 min·I 90
Toward I 90 West: Missoula
15
Take the exit
0.2 mi·30 sec
Toward ID 3: Harrison, Rose Lake, Saint Maries
16
Turn left onto ID 3
33 mi·48 min·South Highway 3
17
Continue on ID 3
0.2 mi·28 sec·South 3rd Street
18
Turn right onto West Jefferson Avenue
49 ft·2 sec·West Jefferson Avenue
19
Arrive at destination
West Jefferson Avenue
Trip Plan
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 245.9 miles from Idaho Falls, ID, or about 3h 58m into the drive.
The longest continuous stretch on this route runs about 256.8 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 108 miles or 1h 45m in
Use this first pause for coffee, a restroom break, and a quick traffic check ahead.
Halfway reset
Around 245.9 miles or 3h 58m 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 245.9 miles or 3h 58m
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 7h 3m
Traffic, exits, and arrival timing usually matter more near Saint Maries, ID than in the middle of the route.
Before You Leave
+
Open the route before leaving Idaho Falls, 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 Idaho Falls, ID
Aim for roughly 246 miles and 4.2 hours of wheel time on this day.
Day 2
Finish the approach into Saint Maries, ID
Aim for roughly 246 miles and 4.2 hours of wheel time on this day.
Your first comfortable stop window is around 108 miles from Idaho Falls, 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 I 90 for about 256.8 miles.
Where to Stop
Rest stops, refuel points, and overnight suggestions along this route.
Halfway Point
Midpoint
About 245.9 mi from Idaho Falls, ID
· 3h 58m into the drive
Station data from NREL Alternative Fuel Stations database.
Driving Electric?
About $52 in charging
· 1 stop
· 66% less CO2
Vehicle Type
kWh
Stops
DC Fast
Home Charge
Average EV
147.5
1
$51.64
$23.61
Efficient EV
123
1
$43.03
$19.67
EV Truck/SUV
196.7
2
$68.85
$31.48
Gas CO2
172 kg
EV CO2
58 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 Apr 15, 2026
Origin
Idaho Falls, ID
Late night
in Idaho Falls on Saturday
Local time
12:09 AM
MDT
Current temp
63°F
Unavailable
Live forecast
Destination
Saint Maries, ID
Night
in Saint Maries on Friday
Local time
11:09 PM
PDT
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.
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 earlier
The destination clock does not match departure time, so double-check hotel check-in windows and late arrival plans.
Temperature spread
19 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
8h 19m 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.
Frequently Asked Questions
The drive from Idaho Falls, ID to Saint Maries, ID covers 491.8 miles and takes about 8h 19m without stops. Add 15-30 minutes for a fuel or rest stop on longer drives.
The main roads are I 90, Veterans Memorial Highway, South Highway 3. Expect a mix of highway and local road driving.
Consider an overnight stop or starting very early.
Yes. This route is usually more comfortable as a 2-day drive. A sensible stopping point is after roughly 246 miles on day one.
The midpoint is about 245.9 miles from Idaho Falls, ID. Look for rest areas, gas stations, or food options near the halfway mark.
At current regular gas prices, expect to spend about $77.93 one way. This estimate uses 25.4 MPG — your actual cost will vary with your vehicle's fuel efficiency and current gas prices.
Start early — leave by 6-7 AM to arrive at a reasonable hour. This is a long drive — plan for a morning departure or consider splitting it into two days.
Plan about 2 meaningful breaks for fuel, food, or rest. Plan on a short reset every 3 to 4 hours to stay fresh behind the wheel.
The route itself is not hard, but at 8h 19m, endurance matters. Plan breaks every 2-3 hours. The 13 decision points are all manageable with basic attention.
The main spots that need attention: near the start (West Stone Run Lane): Navigation decision point; at 0.1 miles (Stonebrook Lane): Navigation decision point; at 2.2 miles (South Utah Avenue): Roundabout - know your exit number before entering.
On the drive from Idaho Falls, ID to Saint Maries, ID, road signs begin pointing toward Rose Lake along the way.
How this page is built
Compiled by the Trip.ovh planning team at COD Solutions Oy from open government datasets — OSRM over OpenStreetMap for geometry, EIA for fuel prices, NREL for EV charging, and NPS for national parks. See our methodology for refresh cadence and limitations.
