General lane use — Iowa Permit Test

On a road with two or more lanes going the same way, the left lane is generally used for passing.

Keeping the left lane open lets faster cars pass without weaving around you.

On a road with two or more lanes traveling in the same direction, the left lane is generally used for passing.

On a road with three or more lanes, stay in the right or center lane except to pass; if a lot of traffic is entering, the center lane is best.

Cars merge in from the right. The center lane keeps you out of their way and leaves the left lane for passing.

If there is a lot of entering traffic, it’s best to use the center lane.

Never drive on the shoulder unless a traffic control device or an official tells you to.

The shoulder is for stopped cars and emergencies. Someone may be parked or walking there.

Unless instructed to do so by a traffic control device or an official, never drive on the shoulder of the road.

Never pass on the shoulder, paved or not; other drivers will not expect you there and may pull off without looking.

A driver ahead may pull onto the shoulder to stop without checking. If you are passing there, you crash.

Never pass on the shoulder, whether it is paved or not.

Where no signs or markings control turning, turn from the lane closest to the direction you want to go, into the lane closest to the one you came from.

Staying in your own lane through a turn keeps you out of the path of cars turning beside you.

Where there are no signs or lane markings to control turning, you should turn from the lane that is closest to the direction you want to go, and turn into the lane closest to the one you came from.

Make turns as directly as possible without crossing lane lines; once the turn is done, you may change lanes if you need to.

Swinging across lanes in the middle of a turn can hit a car beside you. Finish the turn, then move over.

Once you have completed your turn, you can change to another lane if you need to.

On a road with two lanes going your way, what is the left lane mainly for?

Passing. Keeping the left lane open lets faster cars pass without weaving around you. Iowa Driver's License Manual, p.16: “On a road with two or more lanes traveling in the same direction, the left lane is generally used for passing.”