GT4 America Series

The GT4 America Series is a sports car racing series based in the United States. It takes over the GTS class of the Pirelli World Challenge, which adopted global GT4 technical regulations in 2018, and it is a Blancpain GT World Challenge America support series. It is managed by the Stéphane Ratel Organisation and sanctioned by the United States Auto Club.
Classes.
SprintX.
In 2016 an extended sprint format series was added as a standalone championship in addition to its existing Sprint format racing series. SprintX races are 60 minutes in length and feature mandatory driver and tire changes.
GT4 East & GT4 West.
Beginning in 2019, GT4 America began two regional series integrated into its Sprint X Championship. The regional series consist of five rounds each in the eastern and western sides of North America in a two-driver, pro-am format.