National Defense Transportation Day is observed on May 15 and highlights the critical role of transportation systems and personnel in maintaining national security and readiness. This day emphasizes the importance of various transportation methods, including trucks, trains, and planes, in supporting military operations and delivering supplies during emergencies. Celebrations may include attending local transportation expos, listening to guest speaker programs, and recognizing the contributions of transportation workers such as drivers and engineers. Communities are encouraged to engage in activities like bike rides and public transit outings to promote sustainable transportation choices. The day serves as a reminder of how vital transportation is not only in times of crisis but also in everyday life, reinforcing the interconnectedness of the nation's infrastructure.