Territorial expansion History 76 Frontier and pioneer life 35 Expansion territoriale 17 Indians of North America 16 Histoire 15 Colonial question 11 more ... Discovery and exploration 10 Politics and government 9 Description and travel 8 Explorers 7 Pioneers 7 Insular possessions 6 Wars 6 Civilization 5 Foreign relations 5 Imperialism 5 Land settlement 5 Social aspects 5 Influence 4 Race relations 4 Relations 4 Travel 4 Government relations 3 History, Military 3 Mexican War, 1846-1848 3 Political aspects 3 Relations with Indians 3 Social conditions 3 African Americans 2 less ...