The baby boomers, 77 million people born between 1946 and 1964, are the single largest generation in American history. They have changed the face of the United States while placing new demands on the transportation sector. Today, America's "youth generation" is aging. Although older driver safety is a perennial issue, this article does not address this topic; instead, the focus is on the following: Who are the baby boomers, how are they different from previous generations of older people, and what difference does it make for transportation? What will they be doing in old age? Where will they live, and how will they get around? What role might new technologies play in their mobility? What does their retirement mean for the transportation workforce in both government and industry? This article identifies key transportation research questions, policy issues, and practical implications associated with an aging America.