In January 1996, smear- and culture-positive tuberculosis (TB) was diagnosed for a 22-year-old black man after he had traveled on two U.S. passenger trains (29.1 hours) and a bus (5.5 hours) over 2 days. To determine if transmission had occurred, passengers and crew were notified of the potential exposure and instructed to undergo a tuberculin skin test (TST). Of the 240 persons who completed screening, 4 (2%) had a documented TST conversion (increase in induration of ⩾10 mm between successive TSTs), 11 (5%) had a single positive TST (⩾10 mm), and 225 (94%) had a negative TST (Mycobacterium tuberculosis from a potentially highly infectious passenger to other persons during extended train and bus travel.