Is it illegal in IL to drive too slow? Here’s what state law says
While it’s well-known speeding down the road can cause serious accidents, some states, including Illinois, also regulate driving at slower speeds.
The National Highway Traffic Safety Administration reports speeding caused 11,775 deaths in the U.S. in 2023, but driving slower than nearby traffic, especially if you slow down abruptly, can also cause issues.
In addition to general speeding provisions, Illinois law also specifies how motorists may legally use the left lane. Illinois drivers may only use the left lane on the interstate when passing another vehicle, or when no other vehicle is directly behind the vehicle in the left lane or in a few other situations. Neighboring Missouri has similar regulations limiting the lawful use of the left lane on highways.
Here’s what Illinois state law says about generally driving slowly.
Illinois state law on driving too slowly
Illinois state law prohibits motorists from driving slowly enough to impede or block the normal and reasonable traffic flow, with some exceptions.
“The Illinois Vehicle Code does allow law enforcement to pull somebody over and ticket them for driving too slow. ‘Too slow’ is defined as impeding the flow of traffic,” Illinois Legal Aid Online Deputy Director Gwen Daniels said in a June 6 interview with the News-Democrat.
The code’s minimum speed regulation section does not specify a certain slower mileage that may incur a penalty, but minimum speed limits are posted on some Illinois roads, particularly highways.
“It can be as dangerous to drive too slow as it is to drive too fast,” Daniels said.
However, there are certain exceptions under Illinois state law for those driving more slowly, specifically “when reduced speed is necessary for safe operation of his vehicle or in compliance with law.”
If you’re driving in bumper-to-bumper rush hour traffic, Daniels said, you may not be able to safely drive the minimum speed posted. Adverse weather conditions and construction zones may also prohibit safe driving at higher speeds.
The Illinois Secretary of State’s office recommends motorists follow these safe driving tips, some of which have associated laws:
Avoid distracted driving.
Do not drive impaired.
Avoid aggressive driving, such as speeding, tailgating and running red lights.
Yield to emergency vehicles.
Follow posted work zone speed limits and use care around workers.
Follow school zone speed limits and do not pass school buses that are loading or unloading.
Be aware of bicyclists, motorcyclists and pedestrians.
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This story was originally published June 24, 2025 at 5:00 AM.
