^Eastbound US Route 30 where it crosses US Route 52 in Lee County, after a surprise rain shower, October 2021.
US Route 30 runs across northern Illinois, but dodges around Chicago, electing to pass through Joliet instead. It crosses the Mississippi River into Illinois from Clinton, Iowa, heads through Morrison and Rock Falls, and stays a straight east-west rural route across much of north-central Illinois, about 25 miles north of Interstate 80. When it approaches the Aurora area, however, it bypasses Aurora to the south, and dives farther southeasterly through Plainfield and Joliet. From Joliet eastward, it closely parallels Interstate 80 between Joliet and the Indiana state line. It is known for traversing much the same corridor as the historic Lincoln Highway.
The western extent of US Route 30 in Illinois is a bridge over the Mississippi River, carrying traffic out of Clinton, Iowa...
In Fulton, Illinois, the eastern component of Clinton's little metropolis, US Route 30 crosses Illinois 84, which runs along the east side of the Mississippi River:
About two miles farther into Illinois, US Route 30 meets the eastern end of Illinois 136, an extension of Iowa 136:
As US Route 30 approaches Morrison, Illinois 78 joins the route from the north:
In downtown Morrison, Illinois 78 splits from US Route 30 to resume heading south:
In Rock Falls, US Route 30 crosses Illinois 40 (the signal here is now the first I've seen on a northern Illinois state highway to employ the use of flashing yellow arrows):
As US Route 30 begins to exit Rock Falls, it meets an interchange with Interstate 88, which crosses from southwest to northeast (since this is the western extent of the tolled section of Interstate 88, US Route 30 east of here provides a free alternative to the tollway)...
About four miles south of Dixon, US Route 30 crosses Illinois 26:
Near Amboy, a north-south portion of US Route 52 meets a junction with US Route 30:
US Route 30, now north of US Route 52, continues due east to its next junction, with Illinois 251 north of Compton, Illinois (choose fall or winter):
After passing through Shabbona, US Route 30 reaches Waterman, where Illinois 23 crosses it at a 4-way intersection:
After passing through Hinckley and Big Rock, US Route 30 meets an interchange in Sugar Grove home to the western end of the Illinois 56freeway, where US Route 30 joins Illinois 47 south...
Just north of Yorkville and west of Montgomery, US Route 30 splits from Illinois 47 to continue east again:
As US Route 30 is ramping up to cross the Fox River in Montgomery, it creates a fountain interchange to access Illinois 31 below...
That Fox River crossing passes over Illinois 25 with no access, but US Route 30 does access US Route 34, which it joins east, later on in Montgomery...
The concurrency with US Route 34 lasts for less than half a mile, then US Route 30 splits off to head south-southeasterly:
US Route 30 now enters Plainfield, where it joins Illinois 59 south through downtown Plainfield:
US Route 30 now reaches downtown Joliet as a pair of one-way streets, where it crosses another pair of one-way streets carrying Illinois 53, and US Route 6 joins US Route 30 from the south:
The two streets carrying US Route 30, and now also US Route 6, converge at a point just east of downtown, where US Route 6 splits to continue north a short distance: