Illinois state highways numbered in the 200's have a tendency to be former alignments of realigned routes through the state, and Illinois 267 is no different. As you could guess, Illinois 267 is an old routing of US Route 67. Though Illinois 267 is a more direct route from its northern end in Jacksonville to its southern end in Godfrey, the current routing of US67 serves a greater population, including the county seats of Carrollton and Jerseyville. US Route 67 bows westward, staying west of Illinois 267. Illinois 267 hugs the eastern edges of Greene and Jersey Counties, between its northern end in Morgan County and its southern end in Madison County.
Illinois Route 267's northern end is at Illinois 104 and Business Loop 72 in Jacksonville:
The concurrency of Illinois 111 and Illinois 267 continue for the remainder of Illinois 267's length. Arguably, the concurrency could be considered extraneous, but keeping the Illinois 267 designation is beneficial to identify an alternate route to US Route 67: