Tim McGraw will host Swampstock, his hometown charity event, on Sept. 13 in Rayville, La. The event benefits McGraw and Faith Hill's Neighbor's Keeper Foundation. No performers have yet been announced for the event. McGraw recently announced that Swampstock will now be held every two years. The first Swampstock was held in 1994. McGraw launches his new tour in May and will release a two-disc set, titled Greatest Hits: Limited Edition, in Wal-Mart stores on Tuesday (April 29).