Heartland rock is a genre of rock music that is exemplified by singer-songwriters Tom Petty, Bob Seger, Bruce Springsteen and John Mellencamp. It is characterized by a straightforward, often roots musical style, a concern with the average, blue-collar American life, and a conviction that rock music has a social or communal purpose beyond just entertainment. Heartland rock is also associated with a number of country music artists including Steve Earle and Joe Ely, along with less widely known acts such as the Iron City Houserockers. The genre developed in the 1970s and reached its commercial peak in the 1980s, when it became one of the best-selling genres in the United States. In the 1990s, many established acts faded and the genre began to fragment, but the major figures have continued to record with commercial success.