Along with I-270, it forms a loop around the central portion of the bi-state metro area; a majority of I-255 is located on the Illinois half.

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.

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.

North of Sauget, I-255 traverses a portion of the Frank Holten State Recreation Area before an interchange with I-64 west of Caseyville.

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 23 miles (37 km) 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.

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.

[10] As such, the Illinois Department of Transportation (IDOT) concluded a different route number would be necessary for the eastern leg of the beltway.