Interstate 270 (Missouri–Illinois)
Auxiliary Interstate Highway in Illinois and Missouri in the United States
Interstate 270 (I-270) makes up a large portion of the outer belt freeway in Greater St. Louis. The counterclockwise terminus of I-270 is at the junction with I-55 and I-255 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).
Begin with the source’s own compact description: “Interstate 270 (Missouri–Illinois)” is auxiliary Interstate Highway in Illinois and Missouri in the United States. The dossier treats that line as a proposition to test through Interstate, Missouri and Illinois, not as a finished interpretation.
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The citation trail is more important than the brevity of the summary: it shows where individual claims can be examined in context. The source revision retrieved here is dated Aug 15, 2026. The linked authority identifier is Q1072040. Authority coordinates are 38.757, -90.032. 2 of 2 selected statements include explicit references; 0 carry qualifiers and 0 use preferred rank. The first chronological checks are 1978 and 1980.
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This entry incorporates text from “Interstate 270 (Missouri–Illinois)” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.