Interstate 270 in Illinois and Missouri

Interstate 270 in Illinois and Missouri


Get started Mehlville
End Troy
Length 50 mi
Length 81 km
  • 1 → St. Louis / Chicago / Memphis2 Tesson Ferry Road
  • 3 Gravois Road
  • 5 → St. Louis / Springfield
  • 7 Big Bend Road
  • 8 Dougherty Ferry Road
  • 9 Manchester Road
  • 12 → St. Louis / Wentzville
  • 13 Ladue Road
  • 14 Olive Boulevard
  • 16 → St. Charles
  • 17 Dorsett Road
  • 20 → St. Louis / Kansas City
  • 20C St Charles Rock Road
  • 22 → St. Charles
  • 23 James S. McDonnell Boulevard
  • 25 Lindbergh Boulevard
  • 26 → St. Louis Airport
  • 26B Hanley Road
  • 27 New Florissant Road
  • 28 Elizabeth Avenue
  • 29 Florissant Avenue
  • 30 New Halls Ferry Road
  • 30A Old Halls Ferry Road
  • 31 Alton
  • 32 Bellefontaine Road
  • 33 Lilac Avenue
  • 34 Riverview Drive
  • New Chain of Rocks Bridge
  • 3 Granite City / Alton
  • 4 Old Alton Road
  • 6 Pontoon Beach
  • 7 → St. Louis Beltway
  • 9 Glen Carbon
  • 12 Edwardsville
  • 15 → Chicago / Indianapolis

Interstate 270 or I -270 is an Interstate Highway in the US states of Missouri and Illinois. The highway forms a partial ring road around the west and north sides of St. Louis. Along with Interstate 255, I-270 forms a complete ring road around the city. I-270 is 81 kilometers long.

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Travel directions

I-270 with frontage roads.

Interstate 270 on the north side of St. Louis.

The New Chain of Rocks Bridge over the Mississippi River.

Interstate 270 begins at a major interchange with I-55 and I-255 in Mehlville. Interstate 55 comes from Memphis and continues into downtown St. Louis, while Interstate 255 forms the eastern beltway. I-270 then proceeds northwest in 2×4 lanes and serves the western suburbs of St. Louis. At Crestwood one crosses Interstate 44, the highway from Oklahoma City, Tulsa and Springfield to St. Louis. After that, 2×4 lanes are also available while driving through the wooded suburbs. At Creve Coeur you cross the Interstate 64, which runs from the western suburb of Chesterfield toward downtown, and on to Louisville, Kentucky.

I-270 then already runs due north and even has 2×5 lanes. A little further on, at Maryland Heights, one crosses Interstate 70, which comes from Kansas City and heads toward downtown and Indianapolis. Through traffic on I-70 goes here via I-270, as that route rejoins I-70 at the end, is shorter, and avoids downtown St. Louis. Interstate 270 also turns east here, passing the St. Louis airport. State Route 370 ends at Hazelwood, a short bypass of the suburb of St. Charles. I-270 has 2×4 lanes here. Interstate 170. begins at the suburb of Florissant, a short north-south link through the front row of suburbs west of St. Louis. After this, I-270 narrows to 2×3 lanes. One then passes through the suburban area north of St. Louis. At Glasgow Village, the New Chain of Rocks Bridge follows over the Mississippi River, which has 2×2 lanes here.

One then reaches the state of Illinois. One passes by Granite City and intersects Interstate 255, St. Louis’ eastern beltway. To the north, State Route 255 continues as a highway. I-270 then continues for a few more miles to Troy, where the highway ends at an interchange where Interstate 70 continues straight toward Indianapolis and Interstate 55 heads north.

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Interstate 270 is one of the older highways in Missouri. The first section opened in 1962 in the northwestern suburbs. In 1969 the St. Louis bypass on the Missouri side was completed. Formerly, the western bypass, between I-55 and I-70, was known as Interstate 244. In 1966, the New Chain of Rocks Bridge opened over the Mississippi River.

I-270 proved its worth during the great floods of 1993, when the bridge was the only intact bridge across the Mississippi to Keokuk in Iowa, 300 kilometers upstream. In 2010, the interchange with Dorsett Road was transformed into a diverging diamond interchange, one of the first in the United States.


In 2012-2013, I-270 between I-44 and Manchester Road was widened from 2×4 to 2×5 lanes over 5 miles. In December 2012, the 5th lane opened to the north, on October 18, 2013, the 5th lane opened to the south.

Opening history

From Unpleasant Length Opening
Exit 20 Exit 27 11 km 1962
Exit 27 exit 33 10 km 1963
Exit 5 Exit 9 6 km 1964
Exit 9 Exit 14 8 km 1966
exit 33 Exit 3 (IL) 7 km 1966
Exit 14 Exit 20 10 km 1967
Exit 4 Exit 5 2 km 1968
Exit 1 Exit 4 6 km 1969


Except for 2.5 miles, I-270 has 6 or more lanes everywhere. The only narrow section left is north of St. Louis, between Bellefontaine Road and the Illinois border. It is planned to eventually replace the New Chain of Rocks Bridge over the Mississippi River with a wider bridge. On the Illinois side, the bridge over the Mississippi River side channel was replaced between October 2011 and mid-2014.

Traffic intensities

Interstate 270 is a busy highway. There are 145,000 vehicles between I-55 and I-44 and 163,000 vehicles on to I-64. There are 181,000 vehicles up to I-70 and 132,000 vehicles along the north side. 60,000 vehicles cross the Mississippi River every day.

Lane Configuration

The interchange between I-270 and SR-370 in Bridgeton.

From Unpleasant Lanes Comments
exit 0 exit 12 2×5
exit 12 Exit 14 2×4
Exit 14 Exit 23 2×5
Exit 23 Exit 26 2×4
Exit 26 exit 33 2×3
exit 33 Exit 15 2×2 Exit 15 at Illinois

Interstate 270 in Illinois

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