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Interstate 270 in Illinois

Interstate 270 marker

Interstate 270
Route information
Maintained by IDOT and MoDOT
Length: 50.59 mi (81.42 km)
Existed: 1956 – present
Major junctions
CCW end: I-55 / I-255 in Mehlville, MO
  I-44 / US 50 / Route 366 in Sunset Hills, MO
I-64 / US 40 / US 61 in Town and Country, MO
I-70 in Bridgeton, MO
US 67 in Hazelwood, MO
I-170 in Hazelwood, MO
I-255 / IL 255 near Pontoon Beach, IL
CW end: I-55 / I-70 near Troy, IL
Highway system
IL 267 IL I-280
Route 269 MO Route 273

Interstate 270 marker

Interstate 270 (I-270) makes up a large portion of the outer belt freeway in the St. Louis, Missouri metropolitan area. The counterclockwise terminus of I-270 is at the junction with I-55 in Mehlville, Missouri; the clockwise terminus of the freeway is at the junction with I-55 and I-70 north of Troy, Illinois. The entire stretch of I-270 is 50.59 miles (81.42 km).

I-270 between I-70 and I-55 was formerly designated I-244, a western bypass of St. Louis, Missouri. It was originally proposed by Missouri as I-144, but the road was a beltway (or part of one), so the American Association of State Highway and Transportation Officials (AASHTO) assigned it the number I-244. By the late 1970s, the entire beltway (including today's I-255) was integrated as a part of I-270 for consistency. However, the politicians in Illinois started planning their supplemental freeway system in the mid-1970s and a five-mile (8.0 km) section of Corridor 413 was included into the Interstate Highway System in April 1978. This caused a potential place of confusion in Pontoon Beach, Illinois, where I-270 would have intersected itself, and eventually the Illinois Department of Transportation (IDOT) decided on the I-255 numbering in 1980 (but not before considering renumbering an eight-mile (13 km) section to I-870).


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Wikipedia

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