Illinois's primary keep-right and left-lane rules are found in 625 ILCS 5/11-701.
Illinois generally requires vehicles to be driven on the right half of the roadway, subject to statutory exceptions for passing, obstructions, certain marked lane configurations and one-way roadways.
On a two-lane roadway carrying traffic in both directions, a vehicle generally must use the right-hand lane available for traffic, or stay as close as practicable to the right edge of the roadway, except when overtaking and passing another vehicle or preparing for a left turn.
Illinois has a stronger rule for Interstate highways and fully access-controlled freeways. On those roads, a vehicle generally may not be driven in the left lane except when overtaking and passing another vehicle.
The law provides several exceptions to the freeway left-lane rule, including situations involving traffic congestion, snow or other inclement weather, obstructions or hazards in the right lane, compliance with move-over laws, highway design requiring use of the left lane for an exit, toll-road requirements, official traffic-control devices and certain emergency or highway-maintenance vehicles.
This means Illinois is one of the states where the law goes beyond simply requiring unusually slow traffic to keep right: on qualifying Interstate and controlled-access highways, the left lane is generally reserved for passing unless an exception applies.
Exceptions
- Overtaking and passing another vehicle.
- No other vehicle is directly behind the vehicle using the left lane.
- Traffic congestion makes use of the right lane impractical.
- Snow or other inclement weather makes left-lane travel necessary.
- An obstruction or hazard exists in the right lane.
- Changing lanes to comply with Illinois move-over requirements.
- Highway design requires use of the left lane to prepare for an exit.
- Toll-road operation or an official traffic-control device requires use of the left lane.
- Law-enforcement, ambulance, emergency, highway-maintenance and construction vehicles performing official duties.
Penalties
A violation of Illinois's keep-right or left-lane rules is a traffic offense. The total amount due can depend on the specific charge, court costs and other assessments.
Drivers should verify the amount stated on the citation or with the court handling the case, because the total payable amount may vary.
Official Source
625 ILCS 5/11-701 - Drive on Right Side of Roadway; Exceptions
Last verified: October 10, 2026