History of Greater Miami Expressway Agency

The Greater Miami Expressway Agency (GMX), formerly known as the Miami-Dade Expressway Authority (MDX), is an independent state agency responsible for managing and maintaining five key roadways in Miami-Dade and Monroe counties: Airport Expressway SR 112, Dolphin Expressway SR 836, Don Shula Expressway SR 874, Snapper Creek Expressway SR 878, and Gratigny Parkway SR 924 including NW 138th Street. Established in 1994, MDX oversaw these vital roadways, which are now under the management of GMX, following the transition in August 2023.

All five expressways are tolled electronically, requiring either a SunPass transponder or participation in the "toll-by-plate" program. Gratigny Parkway, Don Shula and Snapper Creek Expressways transitioned to all-electronic tolling in 2010, followed by the Airport and Dolphin Expressways in 2014. As an independent state agency, all toll dollars are reinvested into the expressway system.

Today, GMX strives to deliver reliable infrastructure, ensuring efficient and modern transportation for all residents.