Book excerpt: America’s emergence as a global industrial superpower was built on iron and steel, and despite their comparatively small numbers, no immigrant group played a more strategic role per capita in advancing basic industry than Welsh workers and managers. They immigrated in surges synchronized with the stage of America’s industrial development, concentrating in the coal and iron centers of Pennsylvania and Ohio. This book explores the formative influence of the Welsh on the American iron and steel industry and the transnational cultural spaces they created in mill communities in the tristate area—the greater upper Ohio Valley, eastern Ohio, northern West Virginia, and western Pennsylvania—including boroughs of Allegheny County, such as Homestead and Braddock. Focusing on the intersection of transnational immigration history, ethnic history, and labor history, Ronald Lewis analyzes continuity and change, and how Americanization worked within a small, relatively privileged, working-class ethnic group.