This sophisticated book compares the most ambitious and successful single market created in the late nineteenth century, the United States, with its late-twentieth-century counterpart, the EU. The comparison is instructive because, whatever economists may counsel, societies do not simply make choices to maximize economic welfare as a matter of course. Instead, they respond to complex pressures from business interests and legal advocates. Egan maintains that such pressures have ultimately led to similar outcomes on both sides of the Atlantic, generating rules to protect the free movement of goods and, eventually, a single currency, while maintaining local restrictions on service provision and the practice of professions. What differences remain reflect inherited institutional residue. Egan makes a good case, yet substantial differences between the EU and the United States suggest that the underlying commitments to social, political, and ideological integration remain very different in the two regions: one cannot help wondering if Europeans just don’t want a United States of Europe. This is nonetheless an insightful work, particularly for those who follow transatlantic regulatory matters.