Arizona's primary keep-right rule is found in Arizona Revised Statutes §28-721.
On roadways of sufficient width, vehicles generally must be driven on the right half of the roadway unless a statutory exception applies.
A vehicle traveling at less than the normal speed of traffic at the time, place and under the conditions then existing must be driven in the right-hand lane available for traffic, or as close as practicable to the right-hand curb or edge of the roadway.
The slower-traffic rule does not apply when the driver is overtaking and passing another vehicle traveling in the same direction or when preparing for a left turn at an intersection or into a private road or driveway.
Arizona also prohibits driving at such a slow speed that the normal and reasonable movement of traffic is impeded or blocked, unless the reduced speed is necessary for safe operation or required by law.
On certain two-lane highways, a driver traveling below the normal traffic flow must use a designated turnout or another safe turnout area when five or more vehicles are lined up behind and passing is unsafe.
Exceptions
- Overtaking and passing another vehicle traveling in the same direction.
- Preparing for a lawful left turn at an intersection or into a private road or driveway.
- The right half of the roadway is closed because of construction or repair.
- Traveling on certain three-lane roadways under applicable lane rules.
- Traveling on a roadway designated and posted for one-way traffic.
- Driving slowly when the reduced speed is necessary for safe operation or required by law.
Penalties
Arizona traffic-law violations that do not have another specific penalty are generally civil traffic violations and may carry a civil penalty of up to $250.
The exact amount due can depend on the offense, court and applicable assessments. Drivers should verify the amount shown on the citation or with the court handling the case.
Official Source
Arizona Revised Statutes §§28-721 and 28-704 - Keep Right and Minimum Speed Rules
Last verified: October 11, 2026