History Frontier and pioneer life 96 Indians of North America 34 Social conditions 33 History and criticism 31 Territorial expansion 28 Description and travel 23 更多 ... Race relations 23 Women 23 In literature 20 Discovery and exploration 19 Pioneers 19 Social life and customs 18 Travel 18 Politics and government 17 Wars 17 Economic conditions 16 Social aspects 16 Women and literature 15 Womyn 15 African Americans 14 Ethnic relations 13 Military life 13 Railroads 12 Emigration and immigration 11 Overland journeys to the Pacific 11 Western stories 11 World War, 1939-1945 11 American literature 10 Latter Day Saint pioneers 10 少 ...