How far is O'Fallon, MO from Union, MO?
The driving distance from O'Fallon, MO to Union, MO is about 39.5 miles (63.6 km), with a travel time of about 01h 00m by car.
- The straight-line flight distance is about 30 miles (48.2 km).
- For a round trip, plan for roughly 02h 01m of driving time before adding stops, traffic, or weather delays.
- A comfortable departure window is usually 8:00 AM to 10:00 AM CDT.
Reverse, save, or send this route
This route works well as a day trip with time at the destination. Copy the route link, send it to another device, or print a clean version before you head out.
This route works well as a day trip with time at the destination.
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 01h 00m.
A morning start gives you useful time at the destination and keeps the return out of the late evening.
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 Saint Charles County, Missouri, United States
Route Weather Snapshot
Check the forecast at both ends before you head out.
Mostly Sunny
Mostly Sunny
Driving Route Map
The map below follows the saved road route between O'Fallon and Union.
Turn-by-Turn Driving Directions
Step-by-step road directions between O'Fallon and Union.
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1
Start on the route
8 m · 7 sec
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2
Turn left onto South Main Street
3116 ft · 2 min · South Main Street
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3
Turn left onto I 70 East
10 m · 6 sec
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4
Turn sharp left onto South Main Street
87 m · 11 sec · South Main Street
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5
Turn left onto West Terra Lane
576 ft · 12 sec · West Terra Lane
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6
Take the ramp straight toward I 70 West
146 m · 7 sec
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7
Merge slight left
8 mi · 10 min
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8
Take the exit slight right toward MO Z
812 ft · 23 sec
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9
Enter the roundabout and take exit 3 toward South Church Street
74 m · 11 sec · South Church Street
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10
Exit the roundabout onto South Church Street
1 mi · 2 min · South Church Street
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11
Continue straight
1.4 mi · 2 min
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12
Continue straight
4.9 mi · 7 min
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13
Turn right
4.9 mi · 8 min
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14
At the end of the road, turn left
3.1 mi · 4 min
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15
Continue straight
3.6 mi · 6 min
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16
Continue straight
1.1 km · 2 min
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17
At the end of the road, turn left
10 mi · 15 min
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18
Turn right onto East Independence Drive
63 m · 7 sec · East Independence Drive
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19
Turn left onto North Church Street
1.1 km · 2 min · North Church Street
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20
Turn right onto East Park Avenue
900 ft · 31 sec · East Park Avenue
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21
Turn left
19 m · 5 sec
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22
Arrive at your destination
0 m · 1 sec
Car Route Details
A richer read on the saved driving route between O'Fallon and Union.
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.
Longest stretch
At the end of the road, turn left
9.98 mi · 00h 15m
Route Summary
A quick read on whether this route feels easy, ambitious, or worth planning around.
A comfortable day-trip route
This route works well as a day trip. You can leave in the morning, spend meaningful time at the destination, and still return the same day.
Mostly Sunny leaving O'Fallon and Mostly Sunny near Union.
Trip Questions
Direct answers travelers usually want before committing to the drive.
How long does it take to drive from O'Fallon to Union?
The road trip is about 39.5 miles (63.6 km) and usually takes 01h 00m in normal driving conditions.
Is this a same-day trip or an overnight route?
This route works well as a day trip. You can leave in the morning, spend meaningful time at the destination, and still return the same day.
What is the halfway point on this route?
New Melle is a useful midpoint, sitting about 19.8 miles from O'Fallon and 19.8 miles from Union.
How much longer is the road route than the straight-line distance?
The direct path is about 30 miles (48.2 km), while the road route adds roughly 9.5 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 8:00 AM to 10:00 AM CDT. If you want a more comfortable same-day return, try to leave by 4:28 PM CDT.
How much will gas cost for this route?
Using about 28.3 MPG, regular gas is estimated at $5.24 one way or $10.48 round trip. Estimated CO2 is about 12.4 kg one way.
What should you check before leaving?
Before you leave, expect Mostly Sunny around O'Fallon and Mostly Sunny near Union.
Stop Ideas Near New Melle
Useful break, food, and waypoint ideas within about 15 miles of the route midpoint.
City Hall Park
Warrenton City Animal Control
Wentzville City Hall
Transit and Meeting Points
Useful pickup, handoff, or rendezvous points close to New Melle.
Washington
Kirkwood
Hermann
Gateway Transportation Center
Flight Path Map
This map shows the direct air route between O'Fallon and Union. Straight-line distance: 29.97 mi (48.23 km).
#1 O'Fallon
The most populous city in St.
| Population | 89,769 |
| Coordinates | 38.8106100, -90.6998500 |
| Altitude | 165 |
| Country | United States |
#2 Union
City in and county seat of Franklin County, Missouri, United States
| Population | 12,094 |
| Coordinates | 38.4500500, -91.0084800 |
| Altitude | 162 |
| Country | United States |
End: Union (-91.00848, 38.45005)
Estimated Travel Time
Distance: 64 km by road
| Speed | Time |
|---|---|
| 30 mph (48.3 km/h) | 01h 18m |
| 40 mph (64.37 km/h) | 00h 59m |
| 50 mph (80.47 km/h) | 00h 47m |
| 60 mph (96.56 km/h) | 00h 39m |
| 70 mph (112.65 km/h) | 00h 33m |
| 80 mph (129 km/h) | 00h 29m |
Fuel, Round Trip and CO2
Estimated fuel cost and emissions for this route.
| Fuel | $/gal | One way | Round trip |
|---|---|---|---|
| Regular gas | $3.77 | $5.24 | $10.48 |
| Mid-grade | $4.25 | $5.91 | $11.82 |
| Premium | $4.65 | $6.47 | $12.94 |
| Diesel | $5.30 | $7.37 | $14.75 |
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 · Apr 23, 2026
Distance to Other Cities
Planning a road trip? See the full trip guide on Trip.ovh — stops, fuel costs, weather, and departure timing.