I-255's counterclockwise terminus is at an interchange with I-55 and I-270 in Mehlville, Missouri. The beltway is designated as I-270 (with
Kansas City as the control city) west of this interchange and as I-255 east (with
Chicago as the control city) east of this interchange. The section of I-255 east from this interchange to the
Jefferson Barracks Bridge was first built in the 1960s to carry
US 50 traffic across the Mississippi River. The roadway was upgraded between 2002 and 2004. Repairs included both new pavement and the replacement of the
Telegraph Road bridge. Once it crosses the Mississippi River and enters Illinois, I-255 is signed as a north–south highway. It is considerably newer than the Missouri section; it was constructed in the 1980s. At the
IL 3 interchange, I-255 turns sharply to the north. It briefly overlaps with IL 3 in
Dupo. After Dupo, I-255 turns northeast, skirting
Cahokia and
East St. Louis. An interchange at Mousette Lane in
Sauget was constructed in the 1990s and provides motorist access to
GCS Ballpark (home to the
Gateway Grizzlies baseball team) and the
St. Louis Downtown Airport. Given its proximity to the airport, this section of I-255 features shorter light poles to better accommodate takeoffs and landings. North of Sauget, I-255 traverses a portion of the
Frank Holten State Recreation Area before an interchange with
I-64 west of
Caseyville. This section of freeway opened in 1986. Traffic can enter and exit I-255 at an interchange with Collinsville Road (formerly
US 40) just east of the Fairmont Park Racetrack. I-255 meets I-55/I-70 at an interchange in
Collinsville, its original intended terminus. North of this interchange, the control city for I-255 changes from "Chicago" to "To I-270". In the 1980s, I-255 was extended approximately north to meet I-270 in
Pontoon Beach, its current terminus. While the I-255 designation ends at the I-270 interchange, the freeway continues north and west (parallelling the bend in the Mississippi River) for approximately as
IL 255. The decision to not extend the I-255 designation to the new freeway reflects the fact that state and not federal funds were used to pay for construction. ==History==