This guide is designed to provide an overview of careers in transportation, a critical field employing about 10 million people in the United States. The guide is organized in seven sections that cover the following occupational clusters: (1) vehicle operation; (2) passenger assistance; (3) vehicle assembly and maintenance; (4) planning, engineering, and construction; (5) safety and the environment; (6) behind the scenes; and (7) special opportunities in transportation. For each occupation, the number of people working in the occupation, the types of jobs available, the training needed, the expected salary range, and the job duties are summarized. A short eighth section encourages readers to think about transportation in the 21st century. An appendix profiles occupational trends, and seven sources of information are listed. (KC)