Seven truck brands dominate the U.S. heavy-duty market today, but their roots stretch back more than a century. From small regional builders to the backbone of global corporations, these manufacturers shaped the industry that keeps America moving. This media gallery traces the history of each major brand—how they began, the milestones that defined them, and the mergers and transformations that carried them into the modern era. This media gallery is based on a previous Fleets Explained entry on the history of the seven major heavy-duty truck manufacturers in the U.S. For more details, take a look at this article.