United States History 621 20th century 188 Social aspects 143 Histoire 139 États-Unis 133 Biography 116 General 107 History and criticism 97 Political aspects 95 HISTORY 93 Social conditions 85 19th century 80 Politics and government 77 Law and legislation 75 Foreign relations 73 African Americans 67 Government policy 66 Diplomatic relations 61 History & Archaeology 59 SOCIAL SCIENCE / General 59 Americas 55 NON-CLASSIFIABLE 55 USA 55 POLITICAL SCIENCE 53 LAW / General 49 POLITICAL SCIENCE / General 48 HISTORY / General 46 BUSINESS & ECONOMICS 45 HISTORY / United States / General 44