The recent shutdown of the Washington, D.C. metro system due to safety concerns underscored the crucial role that public transportation plays in cities. Riders depend on public transport to reduce commute times and connect to jobs. Public transit eases congestion, contributes to economic development, improves air quality, and conserves energy and resources.

How many people take the metro in U.S. cities and how does ridership in the U.S. compare to the rest of the world?