Federal government-United States-History-19th century 1 Geopolitics-History-19th century Imperialism-History-19th century 1 Nationalism-Southern States-History-19th century 1 Nationalism-United States-History-19th century 1 Secession-Southern States 1 Slaveholders-Southern States-Political activity-History-19th century 1 Slavery-Political aspects-United States-History-19th century 1 Slavery-United States-Justification-History-19th century 1 United States-Territorial expansion 1