Transport, as Colin Clark stated, has been the “maker and breaker of cities”, leading to four successive crises in urban transportation, the last of which is now afflicting cities worldwide. The essence is the problem of dealing with the social costs or exponalities of the growth of private automobile traffic, particularly of a nonconventional (suburb-to-suburb) type. The author discusses various answers to this problem, including new technologies and systems of pricing. Finally he discusses the land-use implication.