Territorial expansion History 303 Imperialism 113 Foreign relations 105 Politics and government 70 International relations 66 Political aspects 50 more ... Frontier and pioneer life 44 Colonies 41 Indians of North America 33 Government relations 27 Social aspects 27 Colonial question 25 Relations 25 Slavery 24 Historiography 23 Race relations 23 Diplomatic relations 22 Discovery and exploration 19 Manifest Destiny 19 Discoveries in geography 18 Philosophy 18 Racism 18 Civilization 17 Extension to the territories 16 Nationalism 16 History and criticism 15 National characteristics, American 15 Colonization 14 Influence 13 less ...