The 2009 Southeastern United States floods were a group of floods that affected several counties throughout northern Georgia, Tennessee, Alabama, Mississippi, and Arkansas. The worst flooding occurred across the Atlanta metropolitan area. Continuous rain, spawned by moisture pulled from the Gulf of Mexico, fell faster than the local watersheds could drain the runoff. The floods were historic, breaking records that went back more than a century in some locations. The Chattahoochee River, the largest river in the region, measured water levels at a 500-year flood level.