In the aftermath of the Spanish-American War, the United States’ acquisition of an overseas empire compelled the nation to reconsider the boundary between domestic and foreign--and between nation and empire. William D. Riddell looks at the experiences of merchant sailors and labor organizations to illuminate how domestic class conflict influenced America’s emerging imperial system. Maritime workers crossed ever-shifting boundaries that forced them to reckon with the collision of different labor systems and markets. Formed into labor organizations like the Sailor’s Union of the Pacific and the International Seaman’s Union of America, they contested the U.S.’s relationship to its empire while capitalists in the shipping industry sought to impose their own ideas. Sophisticated and innovative, On the Waves of Empire reveals how maritime labor and shipping capital stitched together, tore apart, and re-stitched the seams of empire.