Post Falls, ID to Soda Springs, ID is 590.3 miles and takes about 9h 48m via I 90 and I 15, with a fuel budget near $94 and an overnight recommendation. This long-distance drive stays within Idaho, traversing the Mountain West region from north to south. It's a substantial journey that's best broken into two days to avoid feeling rushed. Expect a solid amount of highway driving, so plan accordingly for a trip that covers significant ground across the state.
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
295.2 miles from Post Falls, ID
A natural place for your longest stop of the day
, about 4h 59m into the drive
.
Main Roads
Road
Distance
Duration
I 90
285.1 mi
4h 47m
I 15
269.3 mi
4h 14m
East Merrill Road
31.6 mi
37m
US 30
2.6 mi
3m
North Spokane Street
0.4 mi
1m
West 10th Avenue
0.2 mi
<1m
West 2nd South Street
—
—
Some road-level metrics are being recalculated.
Longest stretch:
I 90
— 285.1 mi, about 4h 47m
Traffic on I-90
Hour-of-day weekday pattern from 58 FHWA count stations on your route.
Peak
4 PM
~981 veh/hr typical
· worst 1,230
Quietest
2 AM
~52 veh/hr
Peak-to-quiet ratio
18.9×
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 Post Falls, ID and Soda Springs, ID.
1
Start on West 10th Avenue
0.2 mi·40 sec·West 10th Avenue
2
Turn right onto North Spokane Street
0.4 mi·1 min·North Spokane Street
3
Turn left
0.4 mi·51 sec
4
Merge onto I 90
285 mi·4 hr 47 min·I 90
5
Take the exit
0.5 mi·1 min
Toward I 15 South: Dillon, Idaho Falls
6
Merge onto I 15
269 mi·4 hr 14 min·I 15
7
Take the exit
0.3 mi·43 sec
Toward I 15 Business, US 30 East: Mc Cammon, Soda Springs, Montpelier
8
Turn left onto I 15 Business; US 30
32 mi·37 min·East Merrill Road
9
Continue on US 30; ID 34
2.6 mi·3 min·US 30; ID 34
10
Arrive at destination
US 30; ID 34
Trip Plan
Given the 9h 48m duration, this trip is comfortably split over two days, with an overnight stop recommended. Aim to depart early on your first day to maximize daylight hours and cover a good portion of the 590.3 miles. Plan for at least two stops to refuel and stretch your legs. A key consideration for this route is managing fuel, especially during the longest stretch on I 90; ensure your tank is full before setting out on that segment. Breaking the drive roughly in half will make the 590.3 miles 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 295.2 miles from Post Falls, ID, or about 4h 59m into the drive.
The longest continuous stretch on this route runs about 285.1 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 130 miles or 2h 12m in
Use this first pause for coffee, a restroom break, and a quick traffic check ahead.
Halfway reset
Around 295.2 miles or 4h 59m 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 295.2 miles or 4h 59m
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 41m
Traffic, exits, and arrival timing usually matter more near Soda Springs, ID than in the middle of the route.
Before You Leave
+
Open the route before leaving Post 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 Post Falls, ID
Aim for roughly 295 miles and 4.9 hours of wheel time on this day.
Day 2
Finish the approach into Soda Springs, ID
Aim for roughly 295 miles and 4.9 hours of wheel time on this day.
Your first comfortable stop window is around 130 miles from Post 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 285.1 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 7
5 decision points cluster between mile 0.2 and 556.1 — GPS handles the exact turns, but know they're coming. Your lane choice matters more than the turn itself.
4
0.2 mi into trip|~0m in|North Spokane Street
Turn right onto North Spokane Street
Navigation decision point
3
0.6 mi into trip|~1m in
Turn left
Navigation decision point
5
286 mi into trip|~4h 50m in
Take the exit toward I 15 South: Dillon, Idaho Falls
Exit ramp - move to the correct lane early. Multiple destination signs - pick the right one
Toward I 15 South: Dillon, Idaho Falls
5
555.8 mi into trip|~9h 5m in
Take the exit toward I 15 Business, US 30 East: Mc Cammon, Soda Springs, Montpelier
Exit ramp - move to the correct lane early. Multiple destination signs - pick the right one
Toward I 15 Business, US 30 East: Mc Cammon, So...
4
556.1 mi into trip|~9h 6m in|I 15 Business; US 30 / East Merrill Road
Turn left onto I 15 Business; US 30 / East Merrill Road
Navigation decision point
Fuel & Cost
Regular Gas
$103.77 one way
$207.53 round trip
$4.47/gal25.4 MPG avg207 kg CO2
Fuel Type
$/gal
One Way
Round Trip
midgrade
$4.67
$108.51
$217.02
premium
$4.99
$115.97
$231.94
diesel
$5.35
$124.33
$248.67
No toll roads detected on this route.
Estimated Trip Cost (one way, 1 person)
Fuel
$104
Hotel (1n)
$80–$140
Meals
$50–$100
Total
$234–$344
Rough estimate based on US averages. Hotel $80–$140/night, meals $25–$50/day.
Estimated CO2 emission: 206.5 kg one way.
Prices: EIA weekly data, 2026-06-01.
Driving Electric?
About $62 in charging
· 2 stops
· 67% less CO2
Vehicle Type
kWh
Stops
DC Fast
Home Charge
Average EV
177.1
2
$61.98
$28.33
Efficient EV
147.6
1
$51.65
$23.61
EV Truck/SUV
236.1
2
$82.64
$37.78
Gas CO2
207 kg
EV CO2
69 kg (67% less)
Plan for 2 charging stops, roughly every 270 miles. Allow 25-40 minutes per stop at a DC fast charger.
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
Post Falls, ID
Afternoon
in Post Falls on Wednesday
Local time
1:07 PM
PDT
Current temp
49°F
Slight Chance Rain Showers
E 2 mph21% chanceLive forecast
Destination
Soda Springs, ID
Afternoon
in Soda Springs on Wednesday
Local time
2:07 PM
MDT
Current temp
32°F
Partly Cloudy
ENE 1 mph0% 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
17 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
9h 48m 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.
More Details
What kind of drive is this?
This route is primarily an interstate experience, with 94% of the drive on major highways like I 90 and I 15. You'll encounter a significant uninterrupted stretch of 285.1 miles on I 90, which means long periods of consistent speed. The majority of the drive will feel like a classic long-haul interstate journey, designed for efficient travel across the landscape. While East Merrill Road is part of the route, its share is minimal compared to the main interstates, suggesting the overall character is one of steady, direct progress.
94% highway — fuel and pacing are the main things to plan.
10 navigation steps total — most of the decisions cluster near the start and finish.
Longest single stretch: 285.1 mi on I 90.
How Hard Is This Drive?
4/10
This is a straightforward highway drive that stays mostly on I 90 and I 15. There are only a few real navigation decisions along the way. The trickiest moment comes around 0.2 miles in near North Spokane Street.
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 9h 48m, endurance matters. Plan breaks every 2-3 hours. The 7 decision points are all manageable with basic attention.
Where does it get tricky?
The main spots that need attention: at 0.2 miles (North Spokane Street): Navigation decision point; at 0.6 miles: Navigation decision point; at 286 miles: Exit ramp - move to the correct lane early. Multiple destination signs - pick the right one.
Elevation Profile
High-altitude sections with notable climbs
5,912 ft2,179 ft
Total Climb
5,977 ft
Total Descent
2,385 ft
Highest Point
5,912 ft
~421.7 mi in
Elevation Range
3,733 ft
Notable High Points
5,881 ft at ~295.2 miles+676 ft prominence
5,912 ft at ~421.7 miles+22 ft prominence
Towns Mentioned on Route Signs
Based on OSRM destination-sign hints, not a full list of every settlement the road passes.
Between Post Falls, ID and Soda Springs, ID, road signs point toward Idaho Falls and Montpelier.
Soda Springs is a city of 3,100 people (2020) in Southeastern Idaho. The city is named for the hundreds of natural springs of carbonated water that are located in and around the city.
The longest stretch is about 285.1 miles on I 90. 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 295 miles on day one.
Yes — we found about 30 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 is a long drive, so arriving tired and in the dark compounds. If the last hour of the trip is on surface roads or mountain grades, aim to arrive at Soda Springs, 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 30 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 0.2 miles (North Spokane Street): Navigation decision point; at 0.6 miles: Navigation decision point; at 286 miles: Exit ramp - move to the correct lane early. Multiple destination signs - pick the right one.
Not recommended in a single day. At 9.8 hours each way, a round trip means 19.6 hours of driving — that is an unsafe level of fatigue for most drivers. Plan at least one night at Soda Springs, ID before the return drive.
