Universities and colleges 151 United States 59 Usage 26 Universities 22 Utopias 21 Underground movements 20 Upper class 20 Urban 19 Underground Railroad 18 Unidentified flying objects 18 Underground railroad 16 Urbanization 16 Unemployment 12 Urban renewal 12 Utilization 12 Undercover operations 11 Unemployed 10 Urban policy 10 Underwater archaeology 9 Uncles 8 Unmarried mothers 8 Urban poor 8 U.S. states 7 Underwater exploration 7 Urban ecology (Sociology) 7 Uniforms 6 Universités 6 User interfaces (Computer systems) 6 Undertakers and undertaking 5 Upper class families 5 Urban health 5 Urban youth 5 University extension 4 Unskilled labor 4 Unternehmen 4 Unterprivilegierung 4 Urban & Land Use Planning 4 Urban beautification 4 Urban economics 4 Urban transportation 4 U-2 Incident, 1960 3 USA 3 Ugliness 3 Umweltpolitik 3 Umweltschutz 3 Uncertainty 3 Uncle Tom (Fictitious character) 3 Underground movements, War 3 Unified field theories 3 Union européenne 3 Unionists (United States Civil War) 3 Unmarried couples 3 Unterricht 3 Upgrading 3 Urban ecology 3 Urban ecology (Biology) 3 Urban geography 3 Urban residence 3 Urban schools 3 Usage des drogues 3 User-generated content 3 Usonian houses 3 Utilitarianism 3 UCSD Pascal (Computer program language) 2 UML (Computer science) 2 Ukiyoe 2 Ultrastructure (Biology) 2 Umwelt 2 Umweltschaden 2 Underground literature 2 Underwater photography 2 Unilateral acts (International law) 2 United Nations 2 United States in art 2 Universidades 2 University cooperation 2 Unrequited love 2 Unternehmensgründung 2 Unterrichtserfolg 2 Upper class women 2 Urban & Regional 2 Urban Health Services 2 Urban Population 2 Urban agriculture 2 Urban animals 2 Urban anthropology 2 Urban folklore 2 Urban landscape architecture 2 Urban transportation policy 2 Urban violence 2 Urban warfare 2 Urbanisme 2 Urine 2 User Generated Content 2 Uxoricide 2 Überlebender 2 U-2 (Reconnaissance aircraft) 1 U-länder 1 U.S. 1 U.S., Executive Branch 1