Thneedville is a city in The Lorax. All the characters except for The Once-ler and The Lorax live there. It was originally named by The Once-ler based on his hit creation, the Thneed. The mayor in the movie was Aloysius O'Hare, owner of the O'Hare Air Company. It's also possible that ThneedVille changed a bit when the townsfolk ditch O'Hare and allow Ted Wiggins to plant the Truffula seed and grow it.
Until the seed was planted, there was no nature in the city, and most of it was made of either plastic or electronics.