Spanning 375 miles across the Great Plains, your journey from Tyndall to Spearfish is a significant cross-state haul that typically takes 6 hours and 31 minutes. You will primarily navigate via I-90, SD Highway 37, and SD Highway 50 to complete the transit. With a fuel budget of approximately $57, this route is best suited for a single, focused day of driving. While it is certainly possible to do this in one go, the duration makes it a substantial commitment behind the wheel. Given the distance, you should plan for at least one dedicated stop to stretch your legs and refuel. Whether you are aiming for an early start or a leisurely pace, keep in mind that the majority of your time will be spent on high-speed transit roads.
Trip Pace
Same-day drive is realistic
A same-day return is possible, but it will make for a full day on the road.
Break Rhythm
1 planned break
Plan on a short reset every 3 to 4 hours to stay fresh behind the wheel.
Midpoint
187.5 miles from Tyndall, SD
A natural place for your longest stop of the day
, about 3h 29m into the drive
.
Main Roads
Road
Distance
Duration
I 90
319.5 mi
5h 4m
SD Highway 37
47.1 mi
1h 10m
SD Highway 50
3.8 mi
5m
303rd Street
1.3 mi
3m
South Highway 37
1 mi
1m
East Jackson Boulevard
0.6 mi
1m
West 20th Avenue
0.5 mi
1m
South Burr Street
0.4 mi
<1m
Longest stretch:
I 90
— 319.5 mi, about 5h 4m
Traffic on I-90
Hour-of-day weekday pattern from 35 FHWA count stations on your route.
Peak
4 PM
~608 veh/hr typical
· worst 856
Quietest
2 AM
~25 veh/hr
Peak-to-quiet ratio
24.3×
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 Tyndall, SD and Spearfish, SD.
1
Start on West 18th Avenue
50 ft·7 sec·West 18th Avenue
2
Turn left onto Main Street
0.2 mi·30 sec·Main Street
3
Turn left onto West 20th Avenue
0.5 mi·1 min·West 20th Avenue
4
Continue on CR 303
1.3 mi·3 min·303rd Street
5
Turn right onto SD 37; SD 50
3.8 mi·5 min·SD Highway 50
6
Turn right onto SD 37
47 mi·1 hr 10 min·SD Highway 37
7
Continue on SD 37
1.0 mi·1 min·South Highway 37
8
Continue on SD 37
0.4 mi·34 sec·South Burr Street
9
Take the ramp
0.4 mi·52 sec
10
Merge onto I 90; SD 37
274 mi·4 hr 19 min·I 90; SD 37
11
Continue on I 90; US 14; SD 79
31 mi·31 min·I 90; US 14; SD 79
12
Continue on I 90; US 14; SD 34
14 mi·14 min·I 90; US 14; SD 34
13
Take the exit
0.3 mi·43 sec
Toward Jackson Boulevard, Black Hills State University
14
Turn left onto East Jackson Boulevard
0.6 mi·1 min·East Jackson Boulevard
15
Turn left onto I 90 Business
149 ft·14 sec·North Main Street
16
Arrive at destination
I 90 Business
Trip Plan
To tackle this 375-mile trip effectively, aim to depart early in the morning to avoid fatigue during the final leg of your journey. Since you have one planned stop, use that time to refuel and grab snacks so you can minimize time spent off the interstate. Because the longest stretch of the drive covers 319.5 miles on I-90, ensure your vehicle is prepped for sustained speeds before you leave Tyndall. Flexibility is your friend on a drive of this length, so keep an eye on your fuel gauge well before you hit that 319-mile interstate segment. By pacing your transit across the state, you can keep the drive manageable and arrive in Spearfish feeling refreshed rather than drained.
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.
You can normally do this drive in one day.
Plan roughly 1 meaningful break for fuel, food, and rest.
The halfway point lands around 187.5 miles from Tyndall, SD, or about 3h 29m into the drive.
The longest continuous stretch on this route runs about 319.5 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 83 miles or 1h 50m in
Use this first pause for coffee, a restroom break, and a quick traffic check ahead.
Halfway reset
Around 187.5 miles or 3h 29m in
This is the best place for your longest stop, a real meal, and a full fuel check.
Final approach
Final hour starts around 5h 29m
Traffic, exits, and arrival timing usually matter more near Spearfish, SD than in the middle of the route.
Before You Leave
+
Open the route before leaving Tyndall, SD 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 Tyndall, SD
This is one driving day of about 375 miles and 6h 31m.
Your first comfortable stop window is around 83 miles from Tyndall, SD.
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 I 90 for about 319.5 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 and 374.4 — 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|Main Street
Turn left onto Main Street
Navigation decision point
4
0.2 mi into trip|~0m in|West 20th Avenue
Turn left onto West 20th Avenue
Navigation decision point
4
5.7 mi into trip|~10m in|SD 37 / SD Highway 37
Turn right onto SD 37 / SD Highway 37
Navigation decision point
5
374.1 mi into trip|~6h 28m in
Take the exit toward Jackson Boulevard, Black Hills State University
Exit ramp - move to the correct lane early. Multiple destination signs - pick the right one
Toward Jackson Boulevard, Black Hills State Uni...
4
374.4 mi into trip|~6h 29m in|East Jackson Boulevard
Turn left onto East Jackson Boulevard
Navigation decision point
Fuel & Cost
Regular Gas
$55.38 one way
$110.76 round trip
$3.75/gal25.4 MPG avg131 kg CO2
Fuel Type
$/gal
One Way
Round Trip
midgrade
$4.14
$61.14
$122.27
premium
$4.72
$69.63
$139.25
diesel
$4.80
$70.81
$141.61
No toll roads detected on this route.
Estimated Trip Cost (one way, 1 person)
Fuel
$55
Meals
$25–$50
Total
$80–$105
Rough estimate based on US averages. Hotel $80–$140/night, meals $25–$50/day.
Estimated CO2 emission: 131.2 kg one way.
Prices: EIA weekly data, 2026-07-13.
Driving Electric?
About $39 in charging
· 1 stop
· 66% less CO2
Vehicle Type
kWh
Stops
DC Fast
Home Charge
Average EV
112.5
1
$39.38
$18.00
Efficient EV
93.8
1
$32.81
$15.00
EV Truck/SUV
150
1
$52.50
$24.00
Gas CO2
131 kg
EV CO2
44 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 Jul 17, 2026
Origin
Tyndall, SD
Evening
in Tyndall on Saturday
Local time
8:15 PM
CDT
Current temp
71°F
Clear
S 10 mph1% chanceLive forecast
Heat Advisory
Heat Advisory issued July 17 at 1:31AM CDT until July 17 at 9:00PM CDT by NWS Sioux Falls SD
Heat Advisory
Heat Advisory issued July 17 at 12:50AM CDT until July 17 at 9:00PM CDT by NWS Aberdeen SD
Destination
Spearfish, SD
Evening
in Spearfish on Saturday
Local time
7:15 PM
MDT
Current temp
68°F
Partly Cloudy
SW 2 mph4% chanceLive forecast
Heat Advisory
Heat Advisory issued July 17 at 1:31AM CDT until July 17 at 9:00PM CDT by NWS Sioux Falls SD
Heat Advisory
Heat Advisory issued July 17 at 12:50AM CDT until July 17 at 9:00PM CDT by NWS Aberdeen SD
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
1 hour earlier
The destination clock does not match departure time, so double-check hotel check-in windows and late arrival plans.
Temperature spread
3 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
6h 31m on the road
Start early — leave by 6-7 AM to arrive at a reasonable hour.
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.
Mount Rushmore National Memorial
National Memorial
Majestic figures of George Washington, Thomas Jefferson, Theodore Roosevelt and Abraham Lincoln, surrounded by the beauty of the Black Hills of South Dakota, tell the story of the birth, growth, devel...
22 mi from route
~54 min detour
Free
near mile 336.2
The rugged beauty of the Badlands draws visitors from around the world. These striking geologic deposits contain one of the world’s richest fossil beds. Ancient horses and rhinos once roamed here. The...
24 mi from route
~61 min detour
$30
near mile 271.6
Park data from the National Park Service API. Alerts update every 2 hours.
More Details
What kind of drive is this?
This trip is heavily highway-focused, with 99% of your travel occurring on major thoroughfares. You should prepare for a consistent, high-speed pace, especially during the 319.5-mile stretch that keeps you locked onto I-90. While the initial segments involve state highways like SD-37 and SD-50, the character of the drive quickly shifts to the steady, repetitive rhythm of the interstate. You won't find many technical curves or complex navigation challenges here; instead, expect a straightforward, efficient drive that prioritizes speed over local scenery. It is a classic Great Plains transit route, offering a clear, predictable path from the southeastern corner of South Dakota all the way to the western edge.
99% highway — fuel and pacing are the main things to plan.
16 navigation steps total — most of the decisions cluster near the start and finish.
Longest single stretch: 319.5 mi on I 90.
How Hard Is This Drive?
3/10
This is a straightforward highway drive that stays mostly on I 90 and SD Highway 37. There are only a few real navigation decisions along the way. The trickiest moment comes early in the drive near Main Street.
Driving Effort3/10
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 6h 31m, 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: near the start (Main Street): Navigation decision point; at 0.2 miles (West 20th Avenue): Navigation decision point; at 5.7 miles (SD 37 / SD Highway 37): Navigation decision point.
Spearfish is in the Black Hills of South Dakota. Although Spearfish is a small community with 14,000 residents, it is the commercial and academic center for several towns in the Black Hills and nearby Wyoming and Montana, attracting more than a million visitors each year with its museums, festivals and natural beauty.
The longest stretch is about 319.5 miles on I 90. The full list of main roads is in the Roads section above.
Yes — we found about 21 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 Spearfish, SD 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 1 meaningful breaks. There are 21 rest areas along the route for bathroom stops.
Mostly yes along the main roads, but rural stretches through SD 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 (Main Street): Navigation decision point; at 0.2 miles (West 20th Avenue): Navigation decision point; at 5.7 miles (SD 37 / SD Highway 37): Navigation decision point.
Yes — Mount Rushmore National Memorial and Badlands National Park. See the National Parks section for detour distances and tips on detours.
Not recommended in a single day. At 6.5 hours each way, a round trip means 13.0 hours of driving — that is an unsafe level of fatigue for most drivers. Plan at least one night at Spearfish, SD before the return drive.
