Q&AZ: Why isn't there an Exit 6 going northbound on Arizona State Route 51?

By Naomi DuBovis
Published: Monday, October 30, 2023 - 5:05am

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Cars traveling down a freeway
Arizona Department of Transportation
A view of State Route 51 and Northern Avenue in Phoenix from an ADOT camera on Oct. 23, 2023.

Driving northbound on Arizona State Route 51, also known as Piestewa Freeway, there’s an Exit 5 toward Glendale Avenue and an Exit 7 toward Northern Avenue.

Through KJZZ’s Q&AZ reporting project, a listener asked: Why isn’t there an Exit 6?

It all comes down to naming conventions and location. Highway exits are named after the mileposts they’re closest to. For the 51, the "Mini Stack" interchange on I-10 marks mile zero. For each mile north, the post number goes up by one.

The exit to Glendale Avenue is closest to the milepost 5, so it was named Exit 5. The same is true for Exit 7. 

Doug Nintzel with the Arizona Department of Transportation said that the distance between the Glendale and Northern exits essentially "skips over" milepost 6. That makes it so milepost 6 is too far from any connecting road. 

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