| U | Unclassified |
| UA | Urbanized area |
| UAM | United Aerial Mapping; Urban Airshed Model (USEPA) |
| UART | Universal Asynchronous Receiver/Transmitter |
| UAS | Urban Area Studies |
| UC | Univ. of California |
| UCAID | Univ. Corp. for Advanced Internet Development |
| UCB | Univ. of California, Berkeley |
| UCD | Univ. of California, Davis |
| UCDL | University of California Digital Library |
| UCGIS | Univ. Consortium for GIS |
| UCLGES | Unified Cartographic Line Graph Encoding System |
| UCPTE | Union for the Coordination of the Production and Transport of Electric Power |
| UCS | Uniform Color Space |
| UCSB | Univ. of California, Santa Barbara |
| UDA | User data area |
| UDB | Universal Data Base |
| UDC | Universal Decimal Classification |
| UDF | Universal Data Format |
| UDNR | Utah Dept. of Natural Resources |
| UDOGM | Utah Division of Oil, Gas and Mining |
| UDP | User Datagram Protocol |
| UDS | Urban Data Solutions |
| UDSL | Utah Division of State Lands |
| UDWR | Utah Division of Water Resources |
| UE | Useful elevation |
| UGB | Urban growth boundary |
| UGC | Utility Graphics Consultants |
| UGID | Universal Geographic Identity |
| UGMS | Utah Geological and Mineral Survey |
| UGSMD | Uganda Geological Survey and Mines Dept. |
| UHF | Ultra-high frequency |
| UHMS | Urban Hydrology Monitoring System |
| UID | User identification |
| UK | United Kingdom |
| U.K. | United Kingdom |
| UKMO | United Kingdom Meteorological Office |
| ULCC | Utility Location and Coordination Council |
| ULSD | Uganda Dept. of Lands and Surveys |
| UML | Unified Modeling Language |
| UN | United Nations |
| UNAM | Universidad Nacional de Mexico |
| UNCLA | Unclassified |
| UNDP | United Nations Development Program |
| UNECA | United Nations Economic Commission for Africa |
| UNEP | United Nations Environment Program |
| UNESCO | United Nations Educational, Scientific and Cultural Organization |
| UNGEGN | United Nations Group of Experts on Geographical Names |
| UNIMACE | Universal Automated Mapping Compilation Equipment |
| Univ. | University |
| UNR | Univ. of Nevada, Reno |
| UP | Urban planning |
| UPADI | Union Panamerica de Asociaciones de Ingenieros |
| UPC | Universal Product Code |
| UPPS | Universal Projection Plotting System |
| UPRN | Unique Property Reference Number |
| UPS | Universal polar stereographic |
| UR | Universal Rectifier |
| U/R | Urban/rural |
| URISA | Urban and Regional Information Systems Assn. |
| URUID | Unrectified image data |
| URL | Universal Resource Locator; Uniform Resource Locator |
| URPI | Unit for Retail Planning Information Ltd. |
| URS | Unrestricted random sample |
| U.S. | United States of America |
| USA | United States of America; United States Army |
| USACE | U.S. Army Corps of Engineers |
| USACERL | U.S. Army Construction Engineering Research Laboratories |
| USAETL | United States Army Engineer Topographic Laboratories |
| USAF | United States Air Force |
| USARP | United States Antarctic Research Program |
| USB | Unified S-Band |
| USBC | United States Bureau of the Census |
| USC | Unified soil classification |
| USC&GS | United States Coast and Geodetic Survey |
| USCE | United States Army Corps of Engineers |
| USCG | United States Coast Guard |
| USCS | United States Customary System |
| USD | Univ. of South Dakota |
| USDA | United States Dept. of Agriculture |
| USDC | United States Dept. of Commerce |
| USDI | United States Dept. of the Interior |
| USEPA | United States Environmental Protection Agency |
| USDMA | United States Defense Mapping Agency |
| USFS | United States Forest Service |
| USFWS | United States Fish and Wildlife Service |
| USGCRP | U.S. Global Change Research Program |
| USGK | Utstredni Sprava Geodezie a Kartografie (Czechoslovakia) |
| USGPO | United States Government Printing Office |
| USGS | United States Geological Survey |
| USGS-MP | United States Geological Survey, Menlo Park |
| USLS | United States Lake Survey |
| USMC | United States Marine Corps |
| USNBS | United States National Biological Survey |
| USN | United States Navy |
| USNCHC | United States National Committee on Scientific Hydrology |
| USNC-ICA | United States National Committee for the ICA |
| USNO | United States Naval Observatory |
| USNOS | United States National Ocean Service (or Survey) |
| USPLSS | U.S. Public Land Survey System |
| USPS | United States Postal Service |
| USR | Universal Space Rectangular (coordinate system) |
| USSCS | United States Soil Conservation Service |
| UST | Underground storage tank |
| UT | Unit terminator; Universal Time; Unorganized territory; Utah |
| UTC | Universal Time Coordinated; Urban Traffic Control System (Siemans) |
| UTM | Universal transverse Mercator |
| UTMS | Universal Mobile Telecommunications Systems |
| UUG | Utstredni Ustav Geologicky |
| UURI | Univ. of Utah Research Inst. |
| UV | Ultraviolet; Unit value |
| UW | Univ. of Washington |
| UWM | Univ. of Wisconsin, Madison |
| UVMap | Urban VMap |
| UWCL | Univ. of Wisconsin Cartography Laboratory (Madison) |
| U-2 | A high altitude remote sensing aircraft |