Illinois Route 177 is an east–west state route in southern Illinois.

This is a distance of 47.59 miles (76.59 km).

[1] Illinois 177 overlaps Illinois Route 160 for about 9 miles (14 km)[3] from south of New Baden to Okawville.

SBI Route 177 originally ran from New Minden to Okawville.

It was extended east to Irvington in 1937, replacing Route 153.