The revolutionary rhetoric of the 18th century hastened the demise of indentured servitude, however, and national independence reinforced the legal status of slavery and increasingly defined manual labor as dependent and racially coded. Bezis-Selfa highlights the importance of slave labour to early American industrial development. Research in documents from the 17th, 18th and early 19th centuries led Bezis-Selfa to accounts of the labour of African-Americans, indentured servants, new immigrants and others. Their stories inform his narrative of more than 200 years of American history.