History Social conditions 162 Motion picture industry 111 Race relations 101 Politics and government 99 Motion pictures 89 Social aspects 85 more ... African Americans 70 Indians of North America 70 Social life and customs 65 Ethnic relations 62 Gold discoveries 61 Economic conditions 52 Mexican Americans 50 Political aspects 45 Emigration and immigration 40 Frontier and pioneer life 40 Environmental conditions 39 Political activity 39 Chinese Americans 36 Civil rights 34 Japanese Americans 34 Description and travel 32 Gold mines and mining 31 Missions 31 Ethnic identity 30 Earthquakes 29 Immigrants 28 Labor unions 28 Civil rights movements 24 less ...