[1] Illinois 127 parallels U.S. Route 51 for its entire length.

U.S. 51 is generally a few miles to the east of Illinois 127, though they never cross.

SBI Route 127 originally ran from Raymond to Carlyle.

In 1944, it was extended west to U.S. Route 66, and south to its current terminus.

[2] A section of Illinois Route 127 south of Carbondale has been designated as the Shawnee Hills Wine Trail by the Illinois state legislature, in commemoration of the region's importance to the Illinois wine industry.