How far is Decatur, IL from Mount Vernon, IL?
The driving distance from Decatur, IL to Mount Vernon, IL is about 122.4 miles (197 km), with a travel time of about 02h 28m by car.
- The straight-line flight distance is about 105.3 miles (169.4 km).
- For a round trip, plan for roughly 04h 57m 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 02h 28m.
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.
Township in Fayette County, Illinois
Route Weather Snapshot
Check the forecast at both ends before you head out.
Mostly Sunny then Chance Showers And Thunderstorms
Mostly Sunny then Chance Showers And Thunderstorms
Driving Route Map
The map below follows the saved road route between Decatur and Mount Vernon.
Turn-by-Turn Driving Directions
Step-by-step road directions between Decatur and Mount Vernon.
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1
Start on East Wood Street
91 m · 16 sec · East Wood Street
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2
Turn left onto South Main Street
1.4 mi · 2 min · South Main Street
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3
Continue on South Business Route 51
3.8 mi · 6 min · South Business Route 51
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4
Take the ramp straight toward South Business Route 51
19.6 mi · 24 min · South Business Route 51
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5
Continue on North 2600 East Rd
7.9 mi · 9 min · North 2600 East Rd
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6
Turn right onto North 2600 East Road
1.6 km · 2 min · North 2600 East Road
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7
Continue on Jackson Street
2668 ft · 2 min · Jackson Street
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8
Turn left onto Cedar Street
142 m · 8 sec · Cedar Street
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9
Turn right onto East 1st Street
2150 ft · 1 min · East 1st Street
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10
Turn left onto South Poplar Street
2138 ft · 30 sec · South Poplar Street
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11
Turn straight onto Fair Avenue
3070 ft · 2 min · Fair Avenue
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12
Continue on County Road 2400 E
2 mi · 3 min · County Road 2400 E
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13
Continue on 300 East Road
15.1 mi · 17 min · 300 East Road
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14
Continue on County Road 875 East
11.1 mi · 13 min · County Road 875 East
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15
Continue on North Kennedy Boulevard
1.5 mi · 2 min · North Kennedy Boulevard
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16
Turn left onto West Gallatin Street
2405 ft · 34 sec · West Gallatin Street
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17
Turn right
554 ft · 7 sec
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18
Continue on United States Highway 51
13.4 mi · 15 min · United States Highway 51
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19
Continue on 250E
10.4 mi · 12 min · 250E
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20
Turn left
7.6 mi · 9 min
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21
Take the exit left
1847 ft · 45 sec
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22
Merge slight left
21.4 mi · 23 min
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23
Take the exit slight right toward IL 15: Ashley, Mt. Vernon
1624 ft · 42 sec
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24
Turn straight onto Broadway Street
2.8 mi · 5 min · Broadway Street
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25
Arrive at your destination
0 m · 1 sec · Broadway Street
Car Route Details
A richer read on the saved driving route between Decatur and Mount Vernon.
Straightforward drive
The saved road route has a manageable number of maneuvers and should be easy to follow with normal attention to signs.
250E
Merge slight left
21.4 mi · 00h 23m
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 then Chance Showers And Thunderstorms leaving Decatur and Mostly Sunny then Chance Showers And Thunderstorms near Mount Vernon.
Trip Questions
Direct answers travelers usually want before committing to the drive.
How long does it take to drive from Decatur to Mount Vernon?
The road trip is about 122.4 miles (197 km) and usually takes 02h 28m 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?
Vandalia is a useful midpoint, sitting about 61.3 miles from Decatur and 61.1 miles from Mount Vernon.
How much longer is the road route than the straight-line distance?
The direct path is about 105.3 miles (169.4 km), while the road route adds roughly 17.1 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 1:32 PM CDT.
How much will gas cost for this route?
Using about 28.3 MPG, regular gas is estimated at $16.29 one way or $32.58 round trip. Estimated CO2 is about 38.4 kg one way.
What should you check before leaving?
Before you leave, expect Mostly Sunny then Chance Showers And Thunderstorms around Decatur and Mostly Sunny then Chance Showers And Thunderstorms near Mount Vernon.
Stop Ideas Near Vandalia
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 Vandalia.
Centralia station
Effingham
Mt. Vernon, IL
Carlinville
Flight Path Map
This map shows the direct air route between Decatur and Mount Vernon. Straight-line distance: 105.27 mi (169.41 km).
#1 Decatur
The most populous city in Macon County, Illinois.
| Population | 70,007 |
| Coordinates | 39.8403100, -88.9548000 |
| Altitude | 205 |
| Country | United States |
#2 Mount Vernon
City located near the center of Jefferson County, Illinois, United States
| Population | 14,511 |
| Coordinates | 38.3172700, -88.9031200 |
| Altitude | 156 |
| Country | United States |
End: Mount Vernon (-88.90312, 38.31727)
Estimated Travel Time
Distance: 197 km by road
| Speed | Time |
|---|---|
| 30 mph (48.3 km/h) | 04h 04m |
| 40 mph (64.37 km/h) | 03h 03m |
| 50 mph (80.47 km/h) | 02h 26m |
| 60 mph (96.56 km/h) | 02h 02m |
| 70 mph (112.65 km/h) | 01h 44m |
| 80 mph (129 km/h) | 01h 31m |
Fuel, Round Trip and CO2
Estimated fuel cost and emissions for this route.
| Fuel | $/gal | One way | Round trip |
|---|---|---|---|
| Regular gas | $3.77 | $16.29 | $32.58 |
| Mid-grade | $4.25 | $18.37 | $36.75 |
| Premium | $4.65 | $20.11 | $40.21 |
| Diesel | $5.30 | $22.91 | $45.83 |
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 18, 2026
Distance to Other Cities
Planning a road trip? See the full trip guide on Trip.ovh — stops, fuel costs, weather, and departure timing.