Any amount over the posted limit is illegal in Illinois, under 625 ILCS 5/11-601. While you might not get pulled over for going 3 mph over the speed limit, there is no legal grace margin.
Illinois Speed Limit Laws by Road Type
Illinois sets different speed limits for different roads and situations as follows:
- Interstates and tollways: 70 mph
- Other highways: 55 mph
- Residential streets: 30 mph
- School zones: 20 mph when children are present
Follow posted signs even if they deviate from these defaults. But if there’s heavy rain on I-55 or construction on Route 47, you’re expected to slow down according to the conditions, even if the sign says 70.
Illinois Laws Against Speeding
Speeding 26-34 mph over the limit is a Class B misdemeanor under Illinois law. If you’re 35+ mph over the limit, it becomes a Class A misdemeanor, which means mandatory court appearances in the county that issued the ticket.
Common excuses, such as “I didn’t see the sign,” won’t get you out of it, and neither will “everyone else was speeding.” Illinois doesn’t recognize ignorance of the law or other drivers’ speeding as valid defenses.
Speeding Penalties and Fines in Illinois
Most speeding violations cost you between $25-$300. But if you go significantly over the limit, you’re looking at $1,000+ once court costs get added.
The bigger threat is license suspension. Three moving violations in 12 months trigger automatic suspension. Points stay on your record for five years, so that ticket can end up costing you thousands in higher car insurance premiums, plus the risk of losing your license.
Special Speed Limit Zones in Illinois
Construction zones can double your fines anywhere in the state. A ticket that would normally cost $150 jumps to $375 whether you’re caught in Peoria, Springfield, Rockford, or on I-90 outside Chicago.
Police watch school zones closely between 7 a.m. and 4 p.m. on school days. If you’re doing 40 in a 20 mph zone, you could look at hefty fines plus potential court appearances.
Minimum Speed Limit Requirements
Many Illinois drivers don’t realize that they can get ticketed for going too slow under 625 ILCS 5/11-604. Highways usually have 45 mph minimums. And blocking traffic without a good reason can get you pulled over, too.
Are There Exceptions That Allow Speeding in Illinois?
Emergency vehicles responding to calls can exceed posted limits. This includes the police, fire trucks, and ambulances. Regular drivers can’t speed under any circumstances. There are no exceptions, even if you think you have a good reason.
How Negligence Applies to Speeding Accidents
While speeding doesn’t automatically make you at fault for a car accident, Illinois uses modified comparative negligence under 735 ILCS 5/2-1116, which means each driver’s fault is examined.
If you’re doing 40 in a 35 zone and someone runs a red light and slams into you, they’re still primarily liable. Your slight speeding doesn’t change much.
But if you’re doing 70 in a 35 zone, that excessive speed can be the dominant factor in determining fault, even if other circumstances played a role in causing the crash.
