This report was prepared for policy makers searching for ways to boost public transit use in U.S. urban areas and wishing to know what can be learned from the experiences of Canada and Western Europe. Describes the differences in public transit use among U.S., Canadian, and Western European cities; identifies those factors, from urban form to automobile usage, that have contributed to these differences; and offers hypotheses about the reasons for these differences--from historical, demographic, and economic conditions to specific public policies, such as automobile taxation and urban land use regulation.