| Record Number | Keyword(s) | Country | Catalog Listed? | Continent | |
| 2771 | U.A.R. | United Arab Republic. | Real | Africa |  |
| 2772 | U.A.R. (denominations in m and f) | Egypt (1958-71). | Real | Africa |  |
| 2773 | U.A.R. (denominations in p) | Syria (1958-61). | Real | Asia |  |
| 2774 | U.G. | Uganda, typewritten stamps (1895). | Real | Africa |  |
| 2775 | U.H. (overprint) | Ecuador, postal tax late fee. | Real | Americas |  |
| 2776 | U.K.T.T. (overprint on stamps of Nigeria) | Cameroons- Southern Cameroons (1960-1). | Real | Australia |  |
| 2777 | U.P.A.E. ADHESION VICTIMAS SAN JUAN Y PUEBLO ARGENTINO | Paraguay, semipostals [For Earthquake Victims of San Juan and the Argentine People]. | Real | Americas |  |
| 2778 | U.R.I. (overprint on stamps of Yugoslavia) | Yugoslavia, unofficial semipostals (1923). | Real | Europe | |
| 2779 | U.S. | United States. | Real | Americas |  |
| 2780 | U.S. POSTAGE | Hawaii (1851). | Real | Americas | |
| 2781 | U.S.A. | United States of America. | Real | Americas |  |
| 2782 | U.S.I.R. (overprint) | United States Internal Revenue. | Real | Americas | |
| 2783 | U.S.P.S. | United States Postage Stamps or Postal Service. | Real | Americas | |
| 2784 | U.S.T.C. (overprint) | India- Cochin (1949) [United States of Travancore-Cochin]. | Real | Asia |  |
| 2785 | UAE (overprint on stamps of Abu Dhabi) | United Arab Emirates (1972). | Real | Africa |  |
| 2786 | UAPCTBO | Bulgaria (1937-44). | Real | Europe |  |
| 2787 | UCAK POSTALARI | Turkey, airmails. | Real | Asia | |
| 2788 | UDMURTIA | Bogus Russian local overprint. | Not Scott Listed | Asia | |
| 2789 | UGANDA (overprint on stamps of British East Africa) | Uganda (1902). | Real | Africa |  |
| 2790 | UGANDA KENYA TANGANYIKA | Kenya, Uganda & Tanzania. | Real | Africa |  |
| 2791 | UGANDA with EAST AFRICA | Kenya, Uganda & Tanzania. | Real | Africa |  |
| 2792 | UGANDA with KENYA | Kenya, Uganda & Tanzania. | Real | Africa |  |
| 2793 | UHURU 1963 | Zanzibar. | Real | Africa |  |
| 2794 | UHURU 9th DEC. 1961 | Tanganyika. | Real | Africa | |
| 2795 | UKRAINE (overprint on stamps of Germany) | Russia- German occupation (1941-3). | Real | Asia |  |
| 2796 | UKRAINIEN FORCES IN BOSNIEN | Overprint on Russian stamps. | Not Scott Listed | Asia | |
| 2797 | UKRAINIEN/MILITARY/CONTINGENT/IN STRUCTURE | Overprint on pairs of Ukraine stamps. | Not Scott Listed | Europe | |
| 2798 | UKRAINSKA NARODNA REPUBLICA | Ukraine [Ukrainian People’s Republic]. | Real | Europe | |
| 2799 | UKRBAT ON UN BOSNIA | Overprint on Ukraine stamps. | Not Scott Listed | Europe | |
| 2800 | UKU LETA | Hawaii [Paid Letter]. | Real | Americas |  |
| 2801 | ULTRAMAR (with a year date, denominations in Avos) | Macao (1911) [Beyond the Sea]. | Real | Asia |  |
| 2802 | ULTRAMAR (with a year date, denominations in Reis) | Portuguese Guinea, war tax stamps (1919) [Beyond the Sea]. | Real | Africa | |
| 2803 | ULTRAMAR (with a year date) | Cuba (1873-6), Puerto Rico (1867-76) [Beyond the Sea]. | Real | Americas |  |
| 2804 | UMBUGGIANISTAN | Hand drawn fantasy for bogus nation. | Not Scott Listed | None | |
| 2805 | UN FORCE (INDIA) CONGO (overprint on stamps of Congo) | India- military stamps (1962). | Real | Asia |  |
| 2806 | UN FORCE W. IRIAN (overprint) | Pakistan- military stamps (1963). | Real | Asia |  |
| 2807 | UNEF (overprint on stamps of India) | India- military stamps (1965). | Real | Asia |  |
| 2808 | UNESCO | France UN Educational, Scientific, and Cultural Org. officials (1961-71) | Real | Europe |  |
| 2809 | UNIAO DOS ATIRADORES CIVIS PORTO FRANCO | Portugal, Rifle club franchise stamps [Union of Civilian Riflemen Free Stamp]. | Real | Europe |  |
| 2810 | UNIE VAN ZUID AFRIKA | South Africa. | Real | Africa |  |
| 2811 | UNION | French produced bogus issue for Philippine islands. | Not Scott Listed | None | |
| 2812 | UNION FRANCAIS | Laos. | Real | Asia |  |
| 2813 | UNION INTERNATIONALE DES TELECOMMUNICATIONS | Switzerland- Int. Telecommunications Union, officials. | Real | Europe |  |
| 2814 | UNION OF SOUTH AFRICA | South Africa. | Real | Africa |  |
| 2815 | UNION PANAMERICANO 1890-1926 CORREO AEREO (overprint) | Guatemala, air mails. | Real | Americas |  |
| 2816 | UNION POSTALE DEL SALVADOR | El Salvador. | Real | Americas |  |
| 2817 | UNION POSTALE UNIVERSELLE with HELVETIA | Switzerland- UPU Int. Bureau, officials (1957-60). | Real | Europe |  |
| 2818 | UNITA-ANGOLA | Stamps supposedly issued by rebel movement in Angola but produced by a stamp dealer. | Not Scott Listed | None |  |
| 2819 | UNITED HORIAN STATES | | Not Scott Listed | None | |
| 2820 | UNITED IRELAND | Fantasy from American Journal of Philately. | Not Scott Listed | None |  |
| 2821 | UNITED REPUBLIC OF TAHCAHYIKAB ZANZIBAR | Tanzania. | Real | Africa |  |
| 2822 | UNITED STATES CITY DISPATCH POST | U.S. Courier stamps- New York City. | Real | Americas |  |
| 2823 | UNTEA (overprint on stamps of Netherlands New Guinea) | West Irian (1962) [United Nations Temporary Executive Authority]. | Real | Asia |  |
| 2824 | UOPTO CKPNCOPN | Romania- Moldavia (1858). | Real | Europe |  |
| 2825 | UPHA ΓOPA | Montenegro- Italian occupation (1941-3). | Real | Europe |  |
| 2826 | URGENCIA | Spain, special delivery. | Real | Europe | |
| 2827 | URGENTE | Spain and Ifni, special delivery. | Real | Europe |  |
| 2828 | URUNDI (overprint on stamps of Congo) | German East Africa- Belgian occupation (1916). | Real | Africa |  |
| 2829 | USKUB (overprint on stamps of Turkey) | Turkey (1911). | Real | Asia |  |
| 3061 | Uganda | Uganda (stamp issuing country) 1962 - | Real | Africa |  |
| 3062 | Uganda Protectorate | Uganda Protectorate (stamp issuing country) 1895 - 1902 | Real | Africa |  |
| 3064 | Ukraine | Ukraine (stamp issuing country) 1992 - | Real | Europe |  |
| 3065 | Ukraine (German Occupation) | Ukraine (German Occupation) (stamp issuing country) 1941 - 1944 | Real | Europe |  |
| 3066 | Ukraine (pre-Soviet) | Ukraine (pre-Soviet) (stamp issuing country) 1918 - 1923 | Real | Europe |  |
| 3067 | Ukrainian Field Post | Ukrainian Field Post (stamp issuing country) 1920 - only | Real | Europe |  |
| 3068 | Umm Al Qiwain | Umm Al Qiwain (stamp issuing country) 1964 - 1967 | Real | Asia |  |
| 3069 | UNESCO | UNESCO (stamp issuing country) 1961 - 1981 | Real | Europe |  |
| 3070 | United Arab Emirates (UAE) | United Arab Emirates (UAE) (stamp issuing country) 1973 - | Real | Asia |  |
| 3071 | United Arab Republic | United Arab Republic (stamp issuing country) 1958 - 1961 | Real | Asia |  |
| 3072 | United Nations (UN) | United Nations (UN) (stamp issuing country) 1951 - | Real | Europe |  |
| 3073 | United Nations Postal Administration | United Nations Postal Administration (stamp issuing country) 1951 - | Real | Europe |  |
| 3075 | Universal Postal Union (UPU) | Universal Postal Union (UPU) (stamp issuing country) 1957 - | Real | Europe |  |
| 3076 | Upper Senegal and Niger | Upper Senegal and Niger (stamp issuing country) 1906 - 1921 | Real | Africa |  |
| 3077 | Upper Silesia | Upper Silesia (stamp issuing country) 1920 - 1922 | Real | Europe |  |
| 3078 | Upper Volta | Upper Volta (stamp issuing country) 1959 - 1984 | Real | Africa |  |
| 3079 | Upper Volta (French Colony) | Upper Volta (French Colony) (stamp issuing country) 1920 - 1933 | Real | Africa |  |
| 3080 | Upper Yafa | Upper Yafa (stamp issuing country) 1967 - only | Real | Asia |  |
| 3081 | Uruguay | Uruguay (stamp issuing country) 1856 - | Real | Americas |  |
| 3082 | US Post Offices in Japan | US Post Offices in Japan (stamp issuing country) 1867 - 1874 | Real | Asia | |
| 3083 | USA | USA (stamp issuing country) 1847 - | Real | Americas |  |
| 3084 | USSR | USSR (stamp issuing country) 1923 - 1992 | Real | Asia |  |
| 3086 | USSR Issues for the Far East | USSR Issues for the Far East (stamp issuing country) 1923 - only | Real | Asia |  |
| 3087 | Uzbekistan | Uzbekistan (stamp issuing country) 1992 - | Real | Asia |  |