In a society of strangers, there develops what can be called crimes of mobility -- forms of criminality rare in traditional societies: bigamy, the confidence game, and blackmail, for example. What they have in common is a kind of fraudulent role-playing, which the new society makes possible. This book explores the social and legal consequences of social and geographical mobility in the United States and Great Britain from the beginning of the 19th century on. Personal identity became more fluid. Lines between classes blurred. Impostors abound.