Published by Center for American Progress. Author: Bonnie Krenz. In September 2017, Puerto Rico’s electricity grid was devastated by Hurricane Maria. Eleven months later, the commonwealth finally reconnected electricity for all of its residents.1 It was the longest, largest blackout in U.S. history and among the largest blackouts in the world. The island’s sole electric utility—the vertically integrated, government-run Puerto Rico Electric Power Authority (PREPA)—faced numerous challenges even before the storm.