Illinois Route 1 is the longest state highway in Illinois, running from Chicago south to a ferry across the Ohio River into Kentucky. For most of its length, it is the easternmost north-south highway in Illinois. It passes through Chicago's south side, many southern suburbs, Danville, Mount Carmel, and other towns.
Illinois 1's northern end is an interchange with Interstate 57's northernmost segment, and it gets its start heading south on Halsted Street on Chicago's South Side:
Illinois 1 crosses Illinois 83 where Harvey meets Riverdale:
Crossing into the Homewood area, Illinois 1 meets an interchange with Interstates 80 and 294 (which run together on the same tollway):
At Chicago Heights, Illinois 1 crosses US Route 30...
Between Crete and Beecher, Illinois 1 joins Illinois 394 south for a short distance:
IDOT decided to stop building the four-lane Illinois 394 at Goodenow Road, a seemingly random traffic signal in Will County. As a result, Illinois 394 ends here as Illinois 1 continues south as a simple two-lane highway:
At the town of Grant Park, Illinois, Illinois 17 comes from the east to join Illinois 1 south...
At Momence, Illinois 1 and Illinois 17 continue together past the western end of Illinois 114:
At Sun River Terrace, Illinois 17 turns off of Illinois 1 to continue west toward Kankakee...
In rural Iroquois County, near Martinton, Illinois 1 crosses US Route 52:
Near the small town of Alvin, Illinois 1 meets a 4-way intersection home to the western end of Illinois 119, as US Route 136 comes from the west to join Illinois 1 south:
In Danville, Illinois 1 continues south through a 4-way intersection where US Route 136 turns off to the east, but US Route 150 joins from the south, forming a replacement concurrency. US Route 136 and US Route 150ricochet off of each other at this juncture:
In Paris, Illinois 1 and US Route 150 become a pair of one-way streets. These one-way streets meet a crossroad that carries Illinois 16 and Illinois 133 to the west, and also carries US Route 150 eastward toward Indiana. This marks the eastern end of both Illinois 16 and Illinois 133, and Illinois 1 continues south without any other route:
At Crossville, Illinois 14 comes from the east to join Illinois 1 south into Carmi:
In Carmi, Illinois 14 splits from Illinois 1 to really start making its way westward across southern Illinois:
At Norris City, Illinois 1 and US Route 45 bounce off of each other, at what I call a "ricochet junction"; both routes make a turn to keep Illinois 1 as the easternmost route:
Near the town of Omaha, Illinois, Illinois 1 crosses Illinois 141:
Illinois 1 crosses Illinois 13 between Equality and Shawneetown:
As Illinois 1 approaches Cave-in-Rock, it meets the eastern end of Illinois 146:
The southern end of Illinois 1 is in Cave-in-Rock, at a ferry carrying vehicles across the river to Kentucky Route 91: