How far is O'Fallon, IL from Cahokia, IL?
The driving distance from O'Fallon, IL to Cahokia, IL is about 18.8 miles (30.3 km), with a travel time of about 00h 26m by car.
- The straight-line flight distance is about 15.2 miles (24.4 km).
- For a round trip, plan for roughly 00h 53m of driving time before adding stops, traffic, or weather delays.
- A comfortable departure window is usually 7:00 AM to 7:00 PM CDT.
Reverse, save, or send this route
This is an easy same-day return drive. Copy the route link, send it to another device, or print a clean version before you head out.
This is an easy same-day return drive.
Flight Distance
Driving Distance
Gas Cost Calculator
Leave and Arrive Planner
Pick a departure time to see your estimated arrival and same-day return window.
Drive time stays fixed at 00h 26m.
This is a short drive, so your comfort window is wide. Traffic and current weather matter more than the clock.
You are leaving earlier than the recommended window, which gives you extra margin for breaks and traffic.
Halfway Point
A useful midpoint for breaks, coffee, or meeting in the middle.
Route Weather Snapshot
Check the forecast at both ends before you head out.
Chance Showers And Thunderstorms
Mostly Sunny then Slight Chance Showers And Thunderstorms
Driving Route Map
The map below follows the saved road route between O'Fallon and Cahokia.
Turn-by-Turn Driving Directions
Step-by-step road directions between O'Fallon and Cahokia.
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1
Start on West State Street
1.5 km · 2 min · West State Street
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2
Enter the roundabout and take exit 2 toward West State Street
22 m · 3 sec · West State Street
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3
Exit the roundabout onto West State Street
998 ft · 28 sec · West State Street
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4
Turn right onto West Highway 50
2559 ft · 51 sec · West Highway 50
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5
Take the ramp slight right
2098 ft · 51 sec
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6
Merge slight left
12.7 mi · 16 min
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7
Keep slight right to continue on IL 3 South: Cahokia
2632 ft · 32 sec
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8
Take the exit slight right toward IL 3 South: Cahokia Heights, Great River Road South
3.6 mi · 6 min
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9
Turn right onto West 1st Street
29 m · 4 sec · West 1st Street
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10
Arrive at your destination
0 m · 1 sec · West 1st Street
Car Route Details
A richer read on the saved driving route between O'Fallon and Cahokia.
Turn-heavy local drive
The route has frequent decision points for its length, so lane choice and turn timing will matter more than cruising speed.
West Highway 50
Merge slight left
12.7 mi · 00h 16m
Route Summary
A quick read on whether this route feels easy, ambitious, or worth planning around.
A short regional drive
This route is short enough to handle as a quick errand, commute, or easy same-day return without much planning overhead.
Chance Showers And Thunderstorms leaving O'Fallon and Mostly Sunny then Slight Chance Showers And Thunderstorms near Cahokia.
Trip Questions
Direct answers travelers usually want before committing to the drive.
How long does it take to drive from O'Fallon to Cahokia?
The road trip is about 18.8 miles (30.3 km) and usually takes 00h 26m in normal driving conditions.
Is this a same-day trip or an overnight route?
This route is short enough to handle as a quick errand, commute, or easy same-day return without much planning overhead.
What is the halfway point on this route?
Rosemont is a useful midpoint, sitting about 9.4 miles from O'Fallon and 9.4 miles from Cahokia.
How much longer is the road route than the straight-line distance?
The direct path is about 15.2 miles (24.4 km), while the road route adds roughly 3.6 extra miles because roads do not follow the straight air line.
When is the best time to leave for this route?
A good departure window is usually 7:00 AM to 7:00 PM CDT. If you want a more comfortable same-day return, try to leave by 7:36 PM CDT.
How much will gas cost for this route?
Using about 28.3 MPG, regular gas is estimated at $2.53 one way or $5.05 round trip. Estimated CO2 is about 6 kg one way.
What should you check before leaving?
Before you leave, expect Chance Showers And Thunderstorms around O'Fallon and Mostly Sunny then Slight Chance Showers And Thunderstorms near Cahokia.
Stop Ideas Near Rosemont
Useful break, food, and waypoint ideas within about 15 miles of the route midpoint.
Transit and Meeting Points
Useful pickup, handoff, or rendezvous points close to Rosemont.
Gateway Transportation Center
Kirkwood
Alton
Carlinville
Flight Path Map
This map shows the direct air route between O'Fallon and Cahokia. Straight-line distance: 15.14 mi (24.36 km).
#1 O'Fallon
Township in St.
| Population | 29,606 |
| Coordinates | 38.5922700, -89.9112100 |
| Altitude | 167 |
| Country | United States |
#2 Cahokia
Village in St.
| Population | 13,742 |
| Coordinates | 38.5708800, -90.1901100 |
| Altitude | 124 |
| Country | United States |
End: Cahokia (-90.19011, 38.57088)
Estimated Travel Time
Distance: 30 km by road
| Speed | Time |
|---|---|
| 30 mph (48.3 km/h) | 00h 37m |
| 40 mph (64.37 km/h) | 00h 28m |
| 50 mph (80.47 km/h) | 00h 22m |
| 60 mph (96.56 km/h) | 00h 18m |
| 70 mph (112.65 km/h) | 00h 16m |
| 80 mph (129 km/h) | 00h 14m |
Fuel, Round Trip and CO2
Estimated fuel cost and emissions for this route.
| Fuel | $/gal | One way | Round trip |
|---|---|---|---|
| Regular gas | $3.77 | $2.53 | $5.05 |
| Mid-grade | $4.25 | $2.85 | $5.70 |
| Premium | $4.65 | $3.12 | $6.24 |
| Diesel | $5.30 | $3.55 | $7.11 |
Assumes 8.3 L/100 km (about 28.3 MPG). CO2 is an estimate and varies by vehicle, fuel blend, traffic, and terrain.
Prices in Illinois · Apr 15, 2026
Distance to Other Cities
Planning a road trip? See the full trip guide on Trip.ovh — stops, fuel costs, weather, and departure timing.