History 51 Indians of North America 36 Frontier and pioneer life 20 Wars 11 African Americans 9 Government relations 6 Description and travel 5 more ... Historiography 5 Territorial expansion 5 Race relations 4 Social life and customs 4 Antiquities 3 Discovery and exploration 3 Environmental policy 3 Frontier thesis 3 Philosophy 3 Political aspects 3 Relations with Indians 3 Slavery 3 Social aspects 3 White people 3 Biography 2 Civilization 2 Colonies 2 Cultural assimilation 2 Discoveries in geography 2 Economic conditions 2 Emigration and immigration 2 Environmental aspects 2 Ethnic relations 2 less ...