How far is Mount Vernon, MO from O'Fallon, MO?
The driving distance from Mount Vernon, MO to O'Fallon, MO is about 241.2 miles (388.1 km), with a travel time of about 03h 57m by car.
- The straight-line flight distance is about 206.8 miles (332.8 km).
- For a round trip, plan for roughly 07h 55m of driving time before adding stops, traffic, or weather delays.
- A comfortable departure window is usually 6:00 AM to 8:00 AM CDT.
Reverse, save, or send this route
This drive is better planned with a longer stop or an overnight stay. Copy the route link, send it to another device, or print a clean version before you head out.
This drive is better planned with a longer stop or an overnight stay.
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 03h 57m.
An early departure helps you fit a real stop into the day without turning the return into a late-night drive.
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.
City in Pulaski County, Missouri, United States
Route Weather Snapshot
Check the forecast at both ends before you head out.
Chance Showers And Thunderstorms then Mostly Sunny
Isolated Showers And Thunderstorms then Chance Showers And Thunderstorms
Driving Route Map
The map below follows the saved road route between Mount Vernon and O'Fallon.
Turn-by-Turn Driving Directions
Step-by-step road directions between Mount Vernon and O'Fallon.
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1
Start on the route
73 m · 24 sec
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2
Turn sharp right
8 m · 9 sec
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3
Turn sharp left onto Market Street
1 km · 2 min · Market Street
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4
Turn left onto East Mount Vernon Boulevard
1.5 km · 2 min · East Mount Vernon Boulevard
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5
Take the ramp left toward I 44 East: Springfield
206.2 mi · 3 hr 43 min
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6
Take the exit slight right toward I 44 Business, MO 100 East: Gray Summit
970 ft · 28 sec
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7
Turn left onto Manchester Road
13.4 mi · 19 min · Manchester Road
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8
Take the exit slight right toward MO 109
1108 ft · 31 sec
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9
Enter the roundabout and take exit 3 toward the route
68 m · 4 sec
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10
Exit the roundabout
157 m · 11 sec
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11
Enter the roundabout and take exit 1 toward the route
30 m · 2 sec
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12
Exit the roundabout
2129 ft · 45 sec
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13
Enter the roundabout and take exit 2 toward the route
29 m · 2 sec
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14
Exit the roundabout
4.3 mi · 7 min
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15
Enter the roundabout and take exit 2 toward South Eatherton Road
29 m · 1 sec · South Eatherton Road
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16
Exit the roundabout onto South Eatherton Road
2.4 mi · 5 min · South Eatherton Road
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17
Continue on Olive Street Road
1.5 km · 2 min · Olive Street Road
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18
Take the ramp left toward Chesterfield Airport Road
1.1 km · 1 min · Chesterfield Airport Road
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19
Merge slight left onto Avenue of the Saints
3.1 mi · 4 min · Avenue of the Saints
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20
Take the exit slight right toward MO K: O'Fallon
100 m · 6 sec
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21
Merge slight right onto North Outer Road
1650 ft · 31 sec · North Outer Road
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22
Continue on North Outer Road
946 ft · 18 sec · North Outer Road
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23
Turn right
3.3 mi · 5 min
-
24
Continue straight
1.5 mi · 3 min
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25
Continue straight
1.6 mi · 3 min
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26
Continue on South Main Street
3115 ft · 2 min · South Main Street
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27
Turn right
8 m · 2 sec
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28
Arrive at your destination
0 m · 1 sec
Car Route Details
A richer read on the saved driving route between Mount Vernon and O'Fallon.
Highway-focused drive
Most of the mileage stays on named highways, so the important moments are ramps, exits, merges, and the final local approach.
I 44 East
Take the ramp left toward I 44 East: Springfield
206 mi · 03h 43m
Route Summary
A quick read on whether this route feels easy, ambitious, or worth planning around.
A longer out-and-back drive
This is still possible in one day, but it becomes a long driving day. Leaving early and planning your stop window matters more here.
Chance Showers And Thunderstorms then Mostly Sunny leaving Mount Vernon and Isolated Showers And Thunderstorms then Chance Showers And Thunderstorms near O'Fallon.
Trip Questions
Direct answers travelers usually want before committing to the drive.
How long does it take to drive from Mount Vernon to O'Fallon?
The road trip is about 241.2 miles (388.1 km) and usually takes 03h 57m in normal driving conditions.
Is this a same-day trip or an overnight route?
This is still possible in one day, but it becomes a long driving day. Leaving early and planning your stop window matters more here.
What is the halfway point on this route?
Saint Robert is a useful midpoint, sitting about 120.5 miles from Mount Vernon and 120.7 miles from O'Fallon.
How much longer is the road route than the straight-line distance?
The direct path is about 206.8 miles (332.8 km), while the road route adds roughly 34.4 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 6:00 AM to 8:00 AM CDT. If you want a more comfortable same-day return, try to leave by 9:04 AM CDT.
How much will gas cost for this route?
Using about 28.3 MPG, regular gas is estimated at $32.09 one way or $64.18 round trip. Estimated CO2 is about 75.6 kg one way.
What should you check before leaving?
Before you leave, expect Chance Showers And Thunderstorms then Mostly Sunny around Mount Vernon and Isolated Showers And Thunderstorms then Chance Showers And Thunderstorms near O'Fallon.
Stop Ideas Near Saint Robert
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 Saint Robert.
Jefferson City
Hermann
Flight Path Map
This map shows the direct air route between Mount Vernon and O'Fallon. Straight-line distance: 206.8 mi (332.81 km).
#1 Mount Vernon
City in Missouri
| Population | 4,477 |
| Coordinates | 37.1036700, -93.8185400 |
| Altitude | 369 |
| Country | United States |
#2 O'Fallon
The most populous city in St.
| Population | 89,769 |
| Coordinates | 38.8106100, -90.6998500 |
| Altitude | 165 |
| Country | United States |
End: (-90.699849, 38.810674)
Estimated Travel Time
Distance: 388 km by road
| Speed | Time |
|---|---|
| 30 mph (48.3 km/h) | 08h 02m |
| 40 mph (64.37 km/h) | 06h 01m |
| 50 mph (80.47 km/h) | 04h 49m |
| 60 mph (96.56 km/h) | 04h 01m |
| 70 mph (112.65 km/h) | 03h 26m |
| 80 mph (129 km/h) | 03h 00m |
Fuel, Round Trip and CO2
Estimated fuel cost and emissions for this route.
| Fuel | $/gal | One way | Round trip |
|---|---|---|---|
| Regular gas | $3.77 | $32.09 | $64.18 |
| Mid-grade | $4.25 | $36.19 | $72.39 |
| Premium | $4.65 | $39.61 | $79.21 |
| Diesel | $5.30 | $45.14 | $90.27 |
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 Missouri · May 31, 2026
Distance to Other Cities
Planning a road trip? See the full trip guide on Trip.ovh — stops, fuel costs, weather, and departure timing.