Tucson Transit Management LLC, doing business as Sun Tran, is the public transit system serving the city of Tucson, Arizona. In 2023, the system had 17,361,800 rides, or about 60,400 per weekday as of the fourth quarter of 2023. 100% of the fleet utilizes clean-burning fuels, such as compressed natural gas (CNG), biodiesel, and hybrid technologies. In addition to more than 40 bus routes, the system also includes the Sun Link modern streetcar line.

Sun Link, also known as the Tucson Streetcar, is a single-line streetcar system in Tucson, Arizona, United States, that began service in July 2014. The system's 3.9-mile (6.3 km) route connects the Arizona Health Sciences Center, the University of Arizona campus, the Main Gate and 4th Avenue shopping and entertainment districts, downtown Tucson, the Tucson Convention Center, and the Mercado District under development west of Interstate 10. The streetcar project's overall cost of $196 million was met through a combination of local funding sources and federal grants. The streetcar shares a common payment system with the Sun Tran regional bus service. In 2023, the line had a ridership of 1,724,900, or about 5,800 per weekday as of the fourth quarter of 2023.