UIUC 81,883 United States 70,539 Universities and colleges 28,422 Urbanization 6,686 U.S. states 5,739 Urban renewal 4,981 Underground movements 4,942 Unemployment 3,727 Unemployed 3,698 Utopias 3,420 Urban policy 3,100 Urban transportation 2,869 Usage 2,614 Ukrainians 1,996 Ukrainian literature 1,810 User interfaces (Computer systems) 1,797 Ukrainian language 1,787 UE/CE Etats membres 1,782 Urbanisme 1,741 Utilization 1,642 Unemployment insurance 1,617 Unitarianism 1,585 USA 1,561 UNITED STATES 1,351 Upper class 1,304 Urban economics 1,276 Universalism 1,267 Urdu literature 1,239 Urban poor 1,214 Urban ecology (Sociology) 1,209 Ukraine 1,187 Unidentified flying objects 1,171 Usury 1,130 Unternehmen 1,121 Uncles 1,116 Uranium ores 1,114 Universités 1,092 Urology 1,082 Undercover operations 1,065 Unterricht 1,064 Umweltschutz 1,054 Uniforms 1,034 Universities 1,033 Uranium 1,001 Ubiquitous computing 1,000 Umweltpolitik 955 Urdu poetry 896 Uncertainty 861 Urologic Diseases 861 Übersetzung 794 Ultrasonic imaging 763 Urban 762 Underground movements, War 757 Unitarian churches 754 Underground press publications 747 Urban runoff 741 Union lists 716 Urdu language 713 Utilitarianism 703 User Interfaces and Human Computer Interaction 691 Ultrasonography 686 University extension 683 Underwater archaeology 677 Unified operations (Military science) 677 Utopias in literature 673 Union catalogs 648 Underground Railroad 641 Unmarried mothers 637 Unitarian Universalist churches 623 Unity 621 User charges 602 Underground dance music 558 Umwelt 553 Urbanisation 551 Underground press 550 Urban schools 535 Urban transportation policy 531 Uranium mines and mining 529 Ukrainian 526 Urinary organs 523 Ukrainian poetry 518 UML 514 Ulama 512 Ultrasonics 494 Universität 491 Ultraviolet radiation 485 Underwater exploration 472 Urban youth 466 Undertakers and undertaking 461 Ukiyoe 457 User-centered system design 452 Urine 441 Usury laws 439 Underground literature 437 Use 436 Uncertainty (Information theory) 435 Unrequited love 425 Underground construction 407 Underground storage 407 Underwater acoustics 405