Newsroom | Loop 303 Corridor: A Key Gateway for Regional Growth

MAG News

The freeway made possible by Proposition 400 is a new hub for regional development and big business looking to move goods closer to customers.

The freeway made possible by Proposition 400 is a new hub for regional development and big business looking to move goods closer to customers

Prop 400

On the Move Partners in Progress logoUnder Proposition 400 in 2004, Maricopa County voters approved an extension of the half-cent sales tax for transportation. This series highlights projects built under Prop 400 — to let you know where your money is going and how it is improving your transportation experience.

What started as a way to connect I-10 in the West Valley to I-17 in the North Valley, the Loop 303 (Estrella Freeway) corridor, has become a significant economic driver for Arizona. 

Industrial-sized distribution centers now sit where farmland used to be. Warehouses spring up like winter grass. The world’s largest semiconductor chipmaker is building a plant in north Phoenix, noting it selected the location because of access to the Loop 303 corridor. 

Jobs and economic development are directly tied to the ability to efficiently move people, goods, and services in, around, and through Maricopa County. Home to more than 4.5 million people, Maricopa County is the fastest-growing and fourth most populous county in the U.S. 

Important Infrastructure Investments

Recently, two new traffic interchanges opened along the Loop 303 corridor at 51st and 43rd avenues, providing direct access to the Taiwan Semiconductor Manufacturing Company. TSMC is the largest contract silicon chip manufacturer in the world. Construction of the interchanges was funded through Maricopa County’s dedicated half-cent sales tax for transportation, known as Proposition 400.

Prop 400 is creating hundreds of thousands of good-paying jobs, growing businesses right here in Arizona, and securing our state’s economic future. Businesses like TSMC choose to invest in Arizona because of our world-class workforce and critical infrastructure investments like Loop 303.
- Arizona Governor Katie Hobbs

Loop 303 a Priority Since 1985

Construction of Loop 303 was first included as part of the Proposition 300 ballot initiative approved by voters in 1985. The project was deferred because of funding shortfalls in the original 20-year plan but included in the Proposition 400 ballot initiative, the first renewal of the dedicated sales tax.

Loop 303 sign with traffic

Designed as a contiguous loop, the 303 will ultimately connect the future State Route 30 in the Southwest Valley to I-17 in north Phoenix. Construction of the full, six-lane freeway between I-10 and Lake Pleasant Parkway has been completed and opened to traffic. The section between Lake Pleasant Parkway and I-17 was constructed as a four-lane interim freeway. An initiative to extend Proposition 400 for 20 years is expected to go before Maricopa County voters in 2024. The funding would include an upgrade to the interim Loop 303 facility to a full freeway from Lake Pleasant Parkway to I-17. 

Investments in Loop 303 Help Bring in Big Business

In early 2020, TSMC announced plans to invest $12 billion to build a facility in north Phoenix along Loop 303. With the addition of the two new traffic interchanges at 51st and 43rd avenues, TSMC now has direct access to the corridor. 

MAG Chair and Phoenix Mayor Kate Gallego credited the dedicated half-cent sales tax for enabling the interchanges to be built quickly. 

Thanks to the funding in Proposition 400, we were able to build these two new interchanges with urgency and meet the growing needs of our community in north Phoenix. A big reason TSMC chose our city for their expansion was our modern transportation infrastructure, and these new traffic improvements are that asset in action.
- Phoenix Mayor Kate Gallego

Distribution Centers Spring Up Along Loop 303

With the completion of Loop 303 from Surprise south to I-10, a wave of economic opportunity rolled into the West Valley. 

“The Loop 303 is a hotbed for development. We've seen billions of dollars in investment from industrial and manufacturing companies around the corridor,” said Chris Camacho, president and CEO of the Greater Phoenix Economic Council (GPEC). 

A network of distribution centers and warehouses now line the southern end of Loop 303. Large companies like Amazon, REI, UPS, Chewy, and Puma have all built or are investing heavily in the stretch of Loop 303 running through Goodyear, Litchfield Park, and Glendale. Investment throughout this corridor is expanding rapidly as companies shift their supply chains out of southern California and into Arizona. 

Distribution center next to the Loop 303 Freeway

Businesses See an Opportunity in the West Valley

Already the investments along the southern leg of Loop 303 are making a difference – not only for businesses, but to everyone in the region.

In 2019, there were 84 businesses and 7,000 jobs in the manufacturing, distribution, and warehousing industries within three miles of Loop 303. Three years later, the number of businesses within those categories doubled, and nearly 3,000 jobs were added. 

•2019 – 84 businesses with 7,000 jobs •2022 – 180 businesses with 9,800 jobs •Business locations up 114 percent •Jobs increase of 41 percent

The investment in building a transportation corridor with easy access to I-10 and southern California will continue attracting business to the Southwest Valley. According to GPEC, more than 35 million consumers can be served within a day’s truck haul, making markets like Nevada, New Mexico, and Texas much easier to reach.

“With accessibility to neighboring markets and a vast talent pool within the region, this type of infrastructure helps Greater Phoenix attract major companies and furthers our competitive edge," Camacho said.

Continued Investment is Needed

As TSMC continues to build the first of two fabrication plants, it has announced plans to increase its original investment of $12 billion to $40 billion, with plans to produce enough advanced chips to meet the U.S. annual demand. The recent growth in development activity around the northern section of Loop 303 highlights the urgency to complete necessary capacity upgrades. Demand along Loop 303 between Lake Pleasant Parkway and I-17 requires the facility to be upgraded to its ultimate condition as a six-lane freeway. 

Loop 303 freeway with TSMC Construction in view

Traffic movements at the existing Loop 303/I-17 interchange will start to fail as early as 2025, based on projected traffic growth associated with the original $12 billion investment by TSMC. Any additional growth in the area will only worsen conditions. Upgrading this intersection to a system interchange will ease congestion and improve traffic flow, allowing TSMC to operate at full capacity. 

These critical improvements to Loop 303 are identified for funding in Phase I of the Regional Strategic Transportation Infrastructure Investment Plan, contingent on voter approval of Proposition 479.

Published November 3, 2023