ADOT 50th anniversary: A timeline of the department's milestones

Shortly after Arizona became a state, the Arizona State Highway Department in 1912.

UPDATED JUL 9, 2024

(Clockwise from top left) Grand opening of Loop 101 from 99th Ave in 1988; Ajo Highway in 1933; a segment of I-10 under construction circa 1968. (Photos: ADOT)

Phoenix, Arizona: The Arizona Department of Transportation turns 50 this month. Governor Katie Hobbs marked the milestone with a letter to ADOT staff highlighting the agency’s accomplishments and innovations, including not just highways but the AZ511 traveler information system and AZMVDNow.com, the online portal through which Motor Vehicle Division customers can conduct dozens of transactions.

The Arizona Department of Transportation was officially established in 1974. (This visual is an AI-generated tribute to ADOT)

“Most importantly, it is ADOT’s dedicated employees, past, present, and future, who shape our state’s transportation system through public service and leadership that ensures AZ families make it to their destinations safely,” Governor Hobbs said.

“Our state is more connected than ever,” ADOT Director Jennifer Toth said. “ADOT employees have worked hard over the decades to expand and improve Arizona’s transportation system. Because of that, people can safely travel throughout our state and businesses can grow.”

Important dates in ADOT's history

1912 Arizona State Highway Department Established: Shortly after Arizona became a state, the Arizona State Highway Department was created to manage the construction and maintenance of state roads.

1927 Arizona Highway Patrol Established: The Arizona Highway Patrol was formed to enforce traffic laws and ensure safety on Arizona’s roads.

1974 Formation of ADOT: The Arizona Department of Transportation was officially established, consolidating the Arizona Highway Department and the Arizona Department of Aeronautics.

1977 Creation of Motor Vehicle Division (MVD): The MVD was created within ADOT to handle driver licensing, vehicle registration, and title services.

1987 ADOT Implements the Adopt a Highway Program: This program encourages community groups and businesses to keep Arizona’s roadways clean by adopting sections of highways.

1990 Launch of the Arizona Scenic Roads Program: ADOT initiated this program to recognize and promote the state's most scenic routes, enhancing tourism and preserving natural beauty.

1995 Implementation of the Environmental Planning Group: ADOT established this group to focus on environmental stewardship and compliance in transportation projects.

2001 ADOT Completes Loop 101 (Pima Freeway): The completion of this major freeway around the Phoenix metropolitan area marked a significant milestone in improving traffic flow and connectivity.

2008 Introduction of Dust Detection System: ADOT installed a dust detection and warning system on parts of Interstate 10 to improve driver safety during dust storms.

2017 Launch of Arizona’s First Diverging Diamond Interchange (DDI): ADOT opened the state's first DDI at Interstate 17 and Happy Valley Road, improving traffic efficiency and safety.

2020 Completion of the Loop 202 South Mountain Freeway: This major freeway project in the Phoenix area was completed, providing a critical link in the regional transportation network.

2021 Use of Drones for Bridge Inspections: ADOT began using drone technology for inspecting bridges, enhancing safety and efficiency in infrastructure maintenance.