"Diversions of Progress" reconstructs the North American West and Pacific as a borderland that materialized through the interplay of cultural economies in the late nineteenth and early twentieth century. By the 1890s, the U.S. West was widely regarded as a symbol of both the nation's primitive past and promising industrial future. Literary Naturalism helped perpetuate the image of this region as an old and new frontier, becoming a genre known for its fantasies of how regenerative contact with the wilderness might still be possible, even if only through nostalgic reproduction. Similar to visions of modernity in commercial pastimes, such as side shows and regional tourist attractions, these stories expressed longing for the nation's fading pastoral landscapes and lost days of white egalitarianism through fears of growing racial diversity and expanding U.S. boundaries. However, as they circulated in the borderlands of California, Mexico, and Hawai'i--regions tied to the U.S. West and to other political, economic, and social cartographies--these cultural forms mirrored as well as diverged from the frontier myth. Popular conceptions of Old California, Old Hawai'i, and Old Mexico as lagging behind the Eastern U.S., moreover, are also contradicted by patterns of borderlands modernization, such as cattle ranching in Hawai'i, cotton growing across Southern California and Baja California, and agriculture in California. Drawing on literary analysis, archival research, and current trends in transnational American studies, I trace the role of material culture in shaping the multiple, converging, and contradictory modernities of this transpacific terrain. I analyze novels by Jack London, Helen Hunt Jackson, and Frank Norris in relation to Wild West and Pacific amusements at San Diego's 1915 world's fair; vice districts in Tijuana and Mexicali; the postcard industry at the U.S.-Mexico border; and Wild West shows featuring Hawaiian cowboys in Hawai'i and the mainland U.S. I contend that these cross-border entertainments illuminate how the West was not a discrete frontier but a border zone in which those deemed racial threats to U.S. national progress--such as Mexicans, native Hawaiians, and Asian immigrants--were both objects and agents of modernity