Territorial expansion History 306 Imperialism 114 Foreign relations 108 Politics and government 70 International relations 68 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 Diplomatic relations 23 Historiography 23 Race relations 23 Discovery and exploration 19 Manifest Destiny 19 Civilization 18 Discoveries in geography 18 Philosophy 18 Racism 18 Extension to the territories 16 Nationalism 16 History and criticism 15 National characteristics, American 15 Colonization 14 Influence 13 less ...