Universities and colleges 1,008
Urbanization 453
Urban policy 259
Urban renewal 255
Unemployment 185
Ultrasonic imaging 180
Urban ecology (Sociology) 172
Utopias 150
User interfaces (Computer systems) 111
Urban poor 107
Usage 99
Ultrasonography 91
Underground movements 87
Urban economics 79
Uncertainty 75
User-Computer Interface 67
Universities 63
Upper class 61
Underwater archaeology 57
Urban transportation 56
Utilization 56
Urban ecology (Biology) 55
United States 51
Utopias in literature 51
Unconscious, Psychology 47
Urban schools 47
Unemployed 46
Urban health 46
Underground Railroad 45
Urban youth 43
Ukrainians 38
User-generated content 36
Utilitarianism 36
Ubiquitous computing 33
Urban Health 33
Urban anthropology 31
Urinary organs 30
Urban agriculture 29
User-centered system design 27
Urban geography 26
Undercover operations 25
Underground press publications 25
Unmarried couples 25
Urban Renewal 24
Underachievers 23
Underground areas 22
Uncertainty (Information theory) 21
Undocumented Immigrants 21
Undocumented immigrants 21
United States Government Agencies 21
Uranium mines and mining 21
Urban violence 21
Urologic Diseases 21
Underwater exploration 20
Urban Indians 20
Urban landscape architecture 20
Urology 20
Unidentified flying objects 19
Urdu language 19
Underground construction 18
Undertakers and undertaking 18
Unjust enrichment 18
Unmarried mothers 18
Urinary catheterization 18
U.S. states 17
Ultrasonography, Prenatal 17
Unemployment insurance 17
Urban warfare 17
Unity 16
University cooperation 16
Urban-rural migration 16
Urinary incontinence 16
Utopian socialism 16
Underground literature 15
Universals (Philosophy) 15
UnrealScript (Computer program language) 15
Urban women 15
Ut pictura poesis (Aesthetics) 15
Unaccompanied immigrant children 14
Unified operations (Military science) 14
Universalism 14
Unskilled labor 14
Upper class women 14
Urban runoff 14
Use 14
Ubuntu (Philosophy) 13
Ultrasonic waves 13
Ultrasonics in obstetrics 13
Urban transportation policy 13
Uterine Cervical Neoplasms 13
Uighur (Turkic people) 12
Ultra-Orthodox Jews 12
Uncles 12
Unemployed youth 12
Uranium 12
Urban dialects 12
Urban parks 12
Ulama 11
Unified field theories 11
Unitarian Universalist churches 11