Territorial expansion History 309 Imperialism 115 Foreign relations 108 Politics and government 72 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 Relations 26 Colonial question 25 Historiography 24 Slavery 24 Diplomatic relations 23 Race relations 23 Discovery and exploration 20 Civilization 19 Discoveries in geography 19 Manifest Destiny 19 Philosophy 18 Racism 18 Extension to the territories 16 History and criticism 16 Nationalism 16 National characteristics, American 15 Colonization 14 Influence 13 less ...