News Releases

Phoenix (December 15, 2025) – As 2025 comes to an end, the Valley is preparing for a new chapter in regional mobility and economic growth. On January 1, 2026, Proposition 479, the voter-approved continuation of Maricopa County’s dedicated half-cent sales tax for transportation will begin a new 20-year cycle of investment in the region’s future. Before that work begins, leaders across the Valley are reflecting on the transformative impact of Proposition 400, which funded a generation of major transportation projects that shaped the region’s success.

Approved by voters in 2004, Proposition 400 extended the half-cent sales tax first established through Proposition 300. Over the last two decades, this investment became the primary engine supporting the region’s multimodal transportation system. Hundreds of freeway, arterial, and transit projects strengthened the region’s economy, connected communities, and helped Maricopa County maintain some of the most reliable commute times among large metropolitan areas in the nation.

“Proposition 400 showed what this region can achieve when we invest in a strong transportation system,” said Glendale Mayor Jerry P. Weiers, Chair of the Transportation Policy Committee. “The half-cent sales tax improved safety, supported economic growth, and kept our communities connected. Proposition 479 will allow us to build on that success and keep Maricopa County moving.”

Key Facts:

Major Prop 400 funded freeway projects include:

• I-10 Broadway Curve Improvement Project – the largest freeway reconstruction project in state history, spanning 11 miles of I-10 between the Loop 202 (Santan/South Mountain Freeway) and I-17
• Loop 202 (South Mountain Freeway)
• Loop 303 (Estrella Freeway)
• State Route 24 (Gateway Freeway)

By The Numbers:

• 452 corridor miles of freeway and highway projects completed.
• 315 corridor miles of arterial projects completed.
• Buses traveled 142 million miles while in service to passengers.
• Receipts from the Prop 400 half-cent sales tax totaled $8.9 billion through Fiscal Year 2025.

Why It Is Important:

Reliable transportation has long been a competitive advantage for Greater Phoenix. These investments support the movement of goods, connect residents to jobs, and allow companies to expand with confidence. This investment is a significant reason why Maricopa County continues to be one of the fastest-growing regions in the United States.

“Proposition 479 will fund critical freeway linkages, including the SR 30 (Tres Rios Freeway), reconstruction of I-17, widening SR 347 and completion of the Loop 303 and SR 24,” said MAG Interim Executive Director John Bullen. “These projects, and the more than 1,000 miles of new or improved streets, will help the region keep one of the best commute times for large cities in the U.S. to an average of 30 minutes into 2050, even with added population and job growth. That is shorter than the current averages for Los Angeles, Chicago, Houston, and Seattle.”

As the Valley transitions from Proposition 400 to Proposition 479, one constant remains. The region is committed to investing in the infrastructure that supports economic prosperity, enhances quality of life, and keeps Maricopa County moving.