Yahoo! Movies has debuted the first US trailer for On the Road, the adaptation of Jack Kerouac’s acclaimed novel from director Walter Salles (The Motorcycle Diaries). The film stars Sam Riley, Garrett Hedlund, and Kristen Stewart as the traveling trio, along with Amy Adams, Kirsten Dunst, Viggo Mortensen, Terrence Howard, Steve Buscemi, Alice Braga, and Elisabeth Moss in supporting roles. On the Road opens December 21st. Trailer and synopsis after the jump.