Not U.S. but north of the border....
2015-08-07 to 08-09: Heavy Montreal (Slipknot, Faith No More, Lamb Of God, Korn, Mastodon, Meshuggah, Testament, Arch Enemy, Extreme, Neurosis, Abbath, Strung Out, Devin Townsend Project, Sanctuary, Swingin' Utters, Veil Of Maya, The Acacia Strain, The Brains, Obscura, After The Burial, Cattle Decapitation, Masked Intruder, Mass Murder Messiah, Sandveiss)
http://heavymontreal.com/