Transportation in the 21st century is entering a robust phase that mirrors the early years of the automobile, when gasoline, steam and electric technology vied for market share. Today, urban transit is making a comeback, as is the electric car. Congested highways still face emission concerns, but consumers now often have the choice of light and heavy rail. Car sharing, which began as a European phenomenon, has prospered in U.S. urban centers, along with bicycle sharing, vanpooling and other options. This special report, produced in coordination with Wharton’s Initiative for Global Environmental Leadership (IGEL), explores how cities are expanding their options for cleaner transportation, and how new technologies, innovations and incentives are revitalizing the sector.