Politics and government Territorial expansion History 18 Imperialism 8 Political aspects 7 Race relations 4 Slavery 4 more ... Extension to the territories 3 Foreign relations 3 Government relations 3 Indians of North America 3 Influence 3 National characteristics, American 3 Political culture 3 Relations 3 Democracy 2 Frontier and pioneer life 2 Louisiana Purchase 2 Manifest Destiny 2 Nationalism 2 Philosophy 2 Political activity 2 Political messianism 2 African Americans 1 Antislavery movements 1 Armenians 1 Balance of power 1 Blacks 1 Citizenship 1 Colonial administrators 1 less ...