Du Page County Highway 21 runs east-west in Northwestern Du Page County. This runs along three different roads. It runs along Geneva Road from Main Street-Glen Ellyn to Coolidge Ave. Washington Street from Collidge Ave. to Illinois State Route 59. Then Fabyan Parkway from Illinois State Route 38 to the Du Page/Kane County Line.
The begin marker at the Du Page/Kane County Line. The western end of DPCH 21 at the Du Page/Kane County Line. The western end marker. WB DPCH 21 in West Chicago. The eastern begin marker on DPCH 21. The end marker at IL St Rt 38.
