The Lorax introduces the story of ThneedVille, a city in which everything is artificial, even the trees. The residents then sing a song about everything their city has to offer and how much they enjoy living in it.
The Lorax confronts the Once-Ler, who has been cutting down Truffula trees to manufacture Thneeds. The two witness the cutting down of the last Truffula tree, marking an end to the viability of the Once-Ler's business. The lack of trees also adversely affects the environment, as is evident by the coughing of the residents of ThneedVille and the migration of all the wildlife.
Ted reveals O' Hare's monopolistic scheme and implores the townspeople to allow him to grow a tree. The call to action inspires several townspeople to voice their support for his mission of planting seeds. When O'Hare suggests inaction and for the trees to die, he learns that no one is on his side.