China's electric power industry is the world's largest electricity producer, passing the United States in 2011 after rapid growth since the early 1990s. In 2019, China produced more electricity than the next three countries—U.S., India, and Russia—combined. China has two wide area synchronous grids, the State Grid and the China Southern Power Grid. The northern power grids were synchronized in 2005.Since 2011 all Chinese provinces are interconnected. The two grids are joined by HVDC back-to-back connections.