Acknowledgements; Abbreviations; Introduction; Prelude: perspectives and problems: the nation, the navy, the stars; Part I. The Founding Era, 1830–65: 1. From depot to national observatory, 1830–46; 2. A choice of roles: the Maury years, 1844–61; 3. Foundations of the American Nautical Almanac Office, 1849–65; 4. Gilliss and the Civil War years; Part II. The Golden Era, 1866–93: 5. Scientific life and work; 6. Asaph Hall, the great refractor and the moons of Mars; 7. William Harkness and the transits of Venus of 1874 and 1882; 8. Simon Newcomb and his work; Part III. The Twentieth Century: 9. Observatory circle: a new site and administrative challenges for the twentieth century; 10. Space: the astronomy of position and its uses; 11. Time: a service for the world; 12. Navigation: from stars to satellites; Summary; Select bibliographical essay; Appendices; Index.