State Route 24 (SR 24), formerly State Route 802 (SR 802), also known as Gateway Freeway and Williams Gateway Freeway, is a freeway in the extreme southeastern region of the Phoenix Metropolitan Area. The roadway is planned as a controlled-access highway to move traffic from the southeastern suburbs of Phoenix to planned ones in northwestern Pinal County. It is the lowest-numbered state route in Arizona. The first mile from Loop 202 to Ellsworth Road opened on May 4, 2014. Planning for future sections has been halted until studies for the Pinal North-South Freeway are completed to confirm how the two freeways will intersect.
Route 24 is a controlled-access highway at the intersection of Loop 202's southern leg (Santan Freeway) and Hawes Road, extending southeast near the Phoenix-Mesa Gateway Airport. Currently extending to Ellsworth Road, the future sections of the roadway plan to continue to the southeast, between the airport and the former General Motors Desert Proving Grounds, until reaching Frye Road, when it turns to the east. The road continues along the Frye Road alignment to the Pinal County line.
Within Pinal County, Route 24 is planned to continue east, intersecting a future north-south freeway under study, and reaching an eastern terminus in the general vicinity of Florence Junction, where US 60 and AZ 79 intersect.
The first mention of a controlled-access highway facility in the Gateway Freeway area occurred in 2003, when the Maricopa Association of Governments's Southeast Maricopa/Northern Pinal County Area Transportation Study identified a freeway starting at Route 202, passing by the Williams Gateway Airport (now Phoenix-Mesa Gateway Airport), and extending east into Pinal County, having its eastern terminus at Route 60. This new freeway was listed as a "potential new regional facility" that would benefit from right-of-way protection. That same year, the Williams Gateway corridor was identified as a new corridor in Maricopa County's Regional Transportation Plan, with construction for the segment within the county planned in the 2016–2020 timeframe. However, the implementation of the plan was based on the assumption that the 1/2¢ sales tax dedicated to transportation would be extended past its expiration at the end of 2005.
In November 2004, voters in Maricopa County approved Proposition 400, an extension to the existing sales tax funding transportation improvements. A portion of those funds are earmarked toward improvements of the county's regional freeway system, which experiences significant volumes of traffic in parts of the Phoenix Metropolitan Area. These improvements are made either through expansion of existing freeways, or the development of new freeway corridors. The Maricopa County portion of the Williams Gateway corridor, as a part of the county's Regional Transportation Plan, was included in the list of projects to be funded with the sales tax.
In 2006, the Maricopa Association of Governments identified a preferred alignment for Route 802 within Maricopa County. The alignment travels southeast from Route 202, between the airport and the former General Motors Desert Proving Grounds, until it turns to the east at Frye Road, continuing eastward to the Pinal County line.
In response to a projected budget shortfall of $6.6 billion brought on by the recession, the Maricopa Association of Governments voted to modify its Regional Transportation Plan by suspend funding to numerous projects during a meeting on October 28, 2009. The Williams Gateway Freeway was among the projects affected, since the construction of most of the Maricopa County portion of the route—the alignment between Ellsworth Road and Meridian Road—was deferred to 2026 or later. An interim roadway between the Santan Freeway and Ellsworth Road would still be constructed in the 2016–2020 time period.
In 2011, the City of Mesa announced it would provide $148 million (2011 USD) to advance construction of the first mile of the freeway, between the Santan Freeway and Ellsworth Road, to provide access to the eastern side of Phoenix-Mesa Gateway Airport. The Arizona State Transportation Board moved construction of the interim facility from fiscal year 2016 to fiscal year 2012, and renumbered the freeway to State Route 24. The interim facility will contain the semi-directional T interchange with the Santan Freeway, consisting of four one-lane ramps; additional traffic lanes on the Santan Freeway; a half-diamond interchange at Ellsworth Road; and a two-lane roadway mainline connecting the two termini of the roadway.
On March 30, 2012, Mesa officials announced plans to start construction the following Friday near Phoenix-Mesa Gateway Airport. Mesa Mayor Scott Smith and Arizona Department of Transportation Director John Halikowski attended a groundbreaking ceremony for the Gateway Freeway, also known as Arizona State Route 24. Mesa officials said in a statement that by issuing bonds, the city was able to speed up construction on the project by four years.
No specific alignment of Route 24 has been set within Pinal County. The study that would determine the preferred alignment for the state route was suspended to allow it to advance in conjunction with the study for the North-South Corridor. However, study maps from the Arizona Department of Transportation show that the freeway's study area in Pinal County runs between the end of the Maricopa County segment and the intersection of U.S. 60 and Arizona 79 in the vicinity of Florence Junction. However, no funds have been identified for the Pinal County segment.