The Arizona Department of Transportation (ADOT) announced today that, following an independent study and public input, it is raising the Interstate 17 speed limit south of Peoria Avenue to 65 mph.

The new speed limit will take effect when ADOT replaces the current 55 mph signs along I-17 between the I-10 “Split” interchange and Peoria Avenue, which is expected to be done by the end of October.

ADOT says that the study determined a 65 mph speed limit within that stretch of I-17 is appropriate since it  more closely reflects the speed most people are currently driving and find reasonable. This is likely to improve compliance, providing an effective tool for law enforcement. The evaluation also notes a 65 mph speed limit can result in more drivers traveling closer to the same speed, which enhances safety. Of the nearly 11,000 people who submitted feedback to the public survey, around 75 percent of respondents supported raising the speed limit to 65 mph.

The study ADOT commissioned followed passage of legislation (SB 1102), which calls for a minimum speed limit of 65 mph on any interstate highway in counties with a population of 3 million or more people. The law stipulates that a lower speed limit can be set if certain conditions are met, including:

  • A lower limit is deemed necessary based on an independent engineering study or roadway assessment.
  • The overall system capacity and mobility along the freeway will not be reduced.
  • An opportunity for public input is provided.

The speed limit is at least 65 mph on all other stretches of interstate highways in the Phoenix area. Maricopa County is Arizona’s only county with a population topping 3 million.

To learn more about how ADOT establishes speed limits, visit


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