Jenny Lewis, The Decemberists, The War On Drugs, Kurt Vile, George Clinton and +35 Acts Scheduled to Perform at Mountain Jam Mountain Jam 2018 has just announced their lineup of live acts with Jack Johnson, Sturgill Simpson, and alt-J headlining the festival. This camping music festival brings out the best in attendees with three days of live music on Hunter Mountain in New York. The event will take place from June 15-17. Additional performing acts include: Portugal. The Man, Jenny Lewis, The Decemberists, The War On Drugs, Kurt Vile and the Violators, George Clinton and Parliament Funk, Rag'n'bone Man, Turkuaz,