Illinois/Major roads

Based off: Functional Classification Maps from IDOT Maps Page

Freeways

These are interstates, highways, freeways, toll roads, and expressways that are multi-lane, divided roads with no stops (no traffic lights, exit and entrance from/to the road is through ramps).

Road	Dir	Northern/ Western End	Southern/ Eastern End	Toll Road?	Notes
I-24	W/E	I-57 South of Marion	KY Border Ohio River	N
I-39	N/S	WI Border	I-55 Normal	N*	Tollway while joined with I-90 from Rockford to WI border.
I-55	N/S	US 41 (Lake Shore Dr / Chicago)	MO Border East St. Louis	N	Known as Stevenson Expressway within Cook County.
I-57	N/S	I-94 Chicago	MO Border Mississippi River	N
I-64	W/E	MO Border East St. Louis	IN Border Wabash River	N
I-70	W/E	MO Border Mississippi River	IN Border	N
I-72	W/E	MO Border Mississippi River	I-57 Champaign	N
I-74	W/E	IA Border Mississippi River	IN Border	N
I-80	W/E	IA Border	IN Border	N*	Tollway portion between I-94 at Thornton and I-294 near Hazel Crest. Tollway portion known as (part of) the Tri-State Tollway.
I-88	W/E	IA Border	I-290/I-294	Y*	Tollway from mile marker 44 (US-30) to eastern terminus. West of US-30 is a freeway. Toll road portion is known as the Ronald Regan Memorial Tollway.
I-90	W/E	WI Border	IN Border	Y*	Tollway from US-51 (WI Border) to east of O'Hare airport (near IL-171 / Cumberland Ave) and from south of Chicago to the IN border. Toll portion from WI border to Chicago area is known as the Jane Addams Memorial Tollway. Freeway portion is known as the Kennedy Expressway north of downtown Chicago (I-290 junction) and Dan Ryan Expressway south of downtown Chicago (I-290 junction). Southeast tollway portion is known as the Chicago Skyway to the IN border.
I-94	W/E*	WI Border	IN Border	N*	Direction of travel in IL is mostly N/S but designation is W/E. Tollway from Deerfield (I-294 junction) to US-41. Tollway portion known as (part of) the Tri-State Tollway. Freeway portion known as the Edens Expressway until it joins I-90.
I-155	N/S	I-74 Morton	I-55 Northwest of Lincoln	N
I-172	N/S	US-24 North of Quincy	I-72 South of Quincy	N	Formerly called the Central Illinois Expressway
I-180	N/S	I-80 Princeton	IL-26 Hennepin	N
I-190	W/E	O'Hare International Airport Chicago	I-90 Chicago	N
I-255	N/S	MO Border Mississippi River	I-270/IL-255 East of Alton	N
I-270	W/E	MO Border Mississippi River	I-70 Northwest of Troy	N
I-280	W/E	IA Border Mississippi River	I-74/I-80 Colona	N
I-290	W/E	I-90 East of Schaumburg	I-90/94 Downtown Chicago	N	Known as the Eisenhower Expressway.
I-294	N/S	I-94 near Lake-Cook County Line	I-80/IL-394 West of Lansing	Y	Known as (part of) the Tri-State Tollway.
I-355	N/S	I-290 Itasca	I-80 New Lenox	Y	Known as the Veterans Memorial Tollway.
I-474	W/E	I-74/IL-6 Peoria	I-74 East Peoria	N

Major Highway

A big highway, usually 3+ lanes, with minimal stops – mostly exits and interchanges, but possibly with some intersections and junctions. In Illinois these are designated as US-XXX or State Rte #.

Road	Dir	Northern/ Western End	Southern/ Eastern End	Notes
IL 83	N/S	north of 31st St. (Oak Brook)	Archer Ave (Lemont)	Continues as Minor Hwy north to xxx

Minor Highways

Usually a narrower highway, 2 lanes or less, that has stops or traffic lights at almost every intersection, but is still a highway (minor US or state highway). These roads are generally important thoroughfare that goes through several cities or towns. In Illinois these are designated as US Rte # or State Rte #.

Road	Dir	Northern/ Western End	Southern/ Eastern End	Notes
IL 83	N/S	Devon Ave (Elk Grove Village)	31st St (Oak Brook)

Primary Street

These are major roads or boulevards in urban and suburban areas and have large amounts of use (such as xx). In less urban environments they are main thoroughfares in towns that are not US or state highways.

Road	Dir	Northern/ Western End	Southern/ Eastern End	Notes
Boughton Rd	W/E	Naperville-Plainfield Rd (Bolingbrook)	Woodward Ave (Woodridge)	Continues east as 87th St

To Be Categorized

These roads still have to be put in their proper places above.

Road	Dir	Northern/ Western End	Southern/ Eastern End	Notes
US 6	W/E	IA-IN borders (Moline - Lansing)		Grand Army of the Republic Highway