Illinois 3 is a long and notable route, stretching from Grafton all the way south along the Mississippi River to the Cairo area, via Alton, East St. Louis, and Chester.
Intersections from north to south:
IL100 at Grafton
IL109 near Newbern
IL111 joins from the north at Alton
US67 at Alton
IL140 intersects at Alton, as IL111 turns eastward onto IL140
IL143 at Wood River
I-270 near Granite City
IL3 joins Interstates 55,64, and 70/US40 west at East St. Louis
IL3 breaks off and heads south
IL157 at Cahokia
IL3 joins I-255/US50 south near Dupo
Then IL3 breaks off near Columbia, as IL158 starts at I-255/US50 and follows IL3 south for a while
IL158 breaks off to head east on the other side of Columbia
IL156 at Waterloo
IL159 at its southern end and IL154 at its western end in Red Bud
IL155 at Ruma
IL3 joins IL150 west for a short distance in Chester
IL3 breaks off of IL150 in Chester
IL151 in western Randolph County
IL149 west of Murphysboro
IL146 joins IL3 south
IL146 heads west after a while toward Cape Girardeau
IL127 at its southern end near Unity
I-57 intersects IL3 as US51, coming from the north on I-57, joins IL3 south
IL3 ends at a point that is also the southern endpoint of IL37, as US51 continues south toward Cairo and Kentucky.
It passes through these towns: Grafton, Godfrey, Alton, East Alton, Wood River, Hartford, Madison, Venice, Brooklyn, E. St. Louis, Cahokia, Dupo, Columbia, Waterloo, Red Bud, Ruma, Evansville, Ellis Grove, Chester, Gale, Olive Branch, Cache.
