On a scorching July afternoon in 1878, at the dawn of the Gilded Age, the moon’s shadow descended on the American West, darkening skies from Montana Territory to Texas. This rare celestial event --- a total solar eclipse --- offered a priceless opportunity to solve some of the solar system’s most enduring riddles, and it prompted a clutch of enterprising scientists to brave the wild frontier in a grueling race to the Rocky Mountains. In vibrant historical detail, AMERICAN ECLIPSE animates the fierce jockeying that came to dominate late 19th-century American astronomy, bringing to life the challenges faced by three of the most determined eclipse chasers who participated in this adventure.