Interstate 255 - History

History

I-255 route was proposed from I-55/I-244 near Green Park to I-55/70 west of Cahokia Mounds near the intersection with IL 111 when plans surfaced in the 1950s Yellow Book. It was originally supposed to be a 4 lane highway but was changed to six lanes.

Since that routing was to go through the American Bottoms, archaeological investigations had to be conducted prior to any constructions, which would later become known as the FAI 270 Series. When Cahokia Mounds was designated in the federal register, a new alignment for I-255 from I-64 to I-55/70 had to be picked.

As a result, this was the last interstate highway in the St. Louis area to be built as construction did not start until the late 1970s. During this time, the entire interstate loop would become I-270. However, the state of Illinois would start making their supplemental freeway plans during this time period and this included a routing from I-55/70 to I-270 in Madison County that would become "Corridor 413".

In 1978, the southern most 6 mile section of Corridor 413 would be added to the Interstate Highway System. This change caused a potential place of confusion where two intersecting highways would have the same number, and IDOT started floating with the I-270/870 routing for the east-west leg in Madison County. The locals did not care for that numbering alternative, as both the Alton Telegraph and Edwardsville Intelligencer was still referring that new highway as I-255 in various articles. In addition, the portion of the Corridor 413 from I-270 to US 67 (then IL 267) was heavily hyped by the local politicians as several nearby highways were already congested by that point of time. By 1980, IDOT decided on the 255 numbering.