How far is Cahokia, IL from O'Fallon, IL?
The driving distance from Cahokia, IL to O'Fallon, IL is about 18.8 miles (30.3 km), with a travel time of about 00h 23m by car.
- The straight-line flight distance is about 15.2 miles (24.4 km).
- For a round trip, plan for roughly 00h 46m 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 23m.
This is a short drive, so your comfort window is wide. Traffic and current weather matter more than the clock.
This departure sits inside the recommended comfort window for the route.
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.
Sunny
Driving Route Map
The map below follows the saved road route between Cahokia and O'Fallon.
Turn-by-Turn Driving Directions
Step-by-step road directions between Cahokia and O'Fallon.
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1
Start on West 1st Street
29 m · 5 sec · West 1st Street
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2
Turn slight left onto Mississippi Avenue
751 ft · 14 sec · Mississippi Avenue
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3
Turn right onto Camp Jackson Road
2.1 mi · 4 min · Camp Jackson Road
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4
Take the ramp slight right toward I 255 North, US 50 East: Chicago
1593 ft · 39 sec
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5
Merge slight left
6.6 mi · 8 min
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6
Take the exit slight right toward I 64, US 50 East: Saint Louis, Louisville
1339 ft · 33 sec
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7
Keep slight right to continue on I 64 East, US 50 East: Louisville
6.9 mi · 9 min
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8
Take the exit slight right toward O'Fallon
1833 ft · 45 sec
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9
Keep slight left to continue on O'Fallon, Hartman Lane
66 m · 5 sec
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10
Keep slight left to continue on O'Fallon
81 m · 9 sec
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11
Turn left onto West Highway 50
1.2 km · 1 min · West Highway 50
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12
Turn left onto West State Street
1043 ft · 29 sec · West State Street
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13
Enter the roundabout and take exit 2 toward W State Street
21 m · 3 sec · W State Street
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14
Exit the roundabout onto W State Street
1.5 km · 2 min · W State Street
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15
Arrive at your destination
0 m · 1 sec · West State Street
Car Route Details
A richer read on the saved driving route between Cahokia and O'Fallon.
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.
I 64 East
Keep slight right to continue on I 64 East, US 50 East: Louisville
6.88 mi · 00h 09m
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.
Sunny leaving Cahokia and Sunny near O'Fallon.
Trip Questions
Direct answers travelers usually want before committing to the drive.
How long does it take to drive from Cahokia to O'Fallon?
The road trip is about 18.8 miles (30.3 km) and usually takes 00h 23m 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 9.3 miles from Cahokia and 9.5 miles from O'Fallon.
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 7:44 PM CDT.
How much will gas cost for this route?
Using about 28.3 MPG, regular gas is estimated at $2.49 one way or $4.98 round trip. Estimated CO2 is about 5.9 kg one way.
What should you check before leaving?
Before you leave, expect Sunny around Cahokia and Sunny near O'Fallon.
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 Cahokia and O'Fallon. Straight-line distance: 15.14 mi (24.36 km).
#1 Cahokia
Village in St.
| Population | 13,742 |
| Coordinates | 38.5708800, -90.1901100 |
| Altitude | 124 |
| Country | United States |
#2 O'Fallon
Township in St.
| Population | 29,606 |
| Coordinates | 38.5922700, -89.9112100 |
| Altitude | 167 |
| Country | United States |
End: West State Street (-89.911209, 38.592282)
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 | $2.49 | $4.98 |
| Mid-grade | $4.25 | $2.81 | $5.61 |
| Premium | $4.65 | $3.07 | $6.14 |
| Diesel | $5.30 | $3.50 | $7.00 |
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 · May 12, 2026
Distance to Other Cities
Planning a road trip? See the full trip guide on Trip.ovh — stops, fuel costs, weather, and departure timing.