Lane usage — Illinois Permit Test

A driver must drive on the right half of the roadway, except in the situations Illinois lists.

Everything else about a two-way road follows from this. The exceptions are all places where the left is the only way through.

You must drive on the right half of the roadway except:

A driver may cross the center line to pass a vehicle moving in the same direction on a two-lane highway, an interstate highway or a controlled freeway.

Passing is the main reason the law lets anyone leave the right half. Naming the roads is how Illinois keeps it to the places built for it.

When passing another vehicle moving in the same direction on a two-lane highway, interstate highway, or controlled freeway.

Where a blockage makes it necessary to drive to the left of the center line, a driver may do so after yielding to oncoming traffic.

A blocked lane leaves one road for two directions. Yielding first is what makes borrowing the other half safe.

When a blockage makes it necessary to drive to the left of the center line. You may drive on the left after yielding to oncoming traffic.

On an interstate highway or a full access controlled freeway, a driver may not use the left lane except to pass another vehicle.

The left lane is a passing lane rather than a fast lane. Sitting in it backs up the drivers trying to get past on the right.

When driving on an interstate highway or full access controlled freeway, you may not drive in the left lane(s) except when passing another vehicle.

A driver may stay in the left lane of an interstate where no other vehicle is directly behind, where traffic or weather makes the right lane impractical, where the right lane is obstructed, or when yielding to emergency or construction vehicles.

The rule is about getting out of somebody’s way, so it lifts when there is nobody there. The other exceptions are places the right lane is unusable.

No other vehicle is directly behind the vehicle being driven in the left lane.

Slow vehicles must use the right-hand lane except when passing or turning left.

A slow vehicle in the left lane makes everybody else weave around it. Keeping right turns one obstacle into a lane traffic can flow past.

Slow vehicles must use the right-hand lane except when passing or turning left.

Weaving from lane to lane to move faster than the flow of traffic is unlawful in Illinois.

Weaving gains a few car lengths and spends everybody else’s reaction time doing it. Illinois names it as an offense rather than bad manners.

Weaving from lane to lane to move faster than the traffic flow is unlawful.

It is unlawful to drive across median strips such as unpaved strips or median barriers, though a driver may turn left across a paved dividing space unless a sign or signal forbids it.

A median is there to keep two directions apart. Crossing it puts a car sideways in front of traffic that has no reason to expect one.

It is unlawful to drive across median strips, such as unpaved strips or median barriers.

A driver may not back up on any shoulder or roadway of a controlled-access roadway, and on other roadways may back up only when it is safe and does not interfere with other vehicles.

Nobody on a freeway is looking for a car coming toward them. On an ordinary road backing is allowed, but only where it surprises nobody.

You may not back up on any shoulder or roadway of any controlled-access roadway.

A driver or passenger may not open a door on the side where traffic is moving unless it can be done safely and without interfering with vehicle or bicycle traffic, and the door may stay open only long enough to load or unload.

A door opened into a bike lane is a wall a cyclist meets at speed. The rule is on the person opening it because only they can see behind.

You or your passenger may not open doors on the side of a vehicle where traffic is moving unless it can be done safely and without interfering with vehicle or bicycle traffic.

Reaching across with the right hand to open the driver door turns the upper body to look behind for oncoming vehicles and bicyclists, which is known as the Dutch Reach.

Using the near hand lets you open the door without turning. The far hand makes you look, which is the whole of the technique.

You should consider using their right hand to open the vehicle door to allow them to turn and check for oncoming vehicles and bicyclists.

It is illegal to take part in a street sideshow, where vehicles block or impede traffic on a street or highway to perform stunts, speed contests or exhibitions of speed.

A sideshow closes a public road with cars and a crowd. Illinois names it so that being one of the blocking vehicles is itself the offense.

It is illegal to engage in a street sideshow, which is an event in which one or more vehicles block or impede traffic on a street or highway to perform unauthorized motor vehicle stunts, motor vehicle speed contests, or motor vehicle exhibitions of speed.

Which half of an Illinois roadway must a driver normally use?

The right half. Everything else about a two-way road follows from this. The exceptions are all places where the left is the only way through. Illinois Rules of the Road 2026, p.29: “You must drive on the right half of the roadway except:”