| Toby Point Observatory | Narragansett | — |
| Tortugas Mountain Observatory | New Mexico | — |
| Torus Observatory | Buckley | — |
| Transit Dreams Observatory, Campobello | Campobello | — |
 Transition Region and Coronal Explorer | — | — |
| Trumbull Observatory | Trumbull | — |
| Tucson Magnetic Observatory | — | — |
| Tucson-Winterhaven observatory | Tucson | — |
| Tumamoc Hill observatory | Tucson | — |
| Tyrone observatory | condado de Grant | — |
| Tzec Maun Observatory | Mayhill | — |
| U. of Minn. Infrared Observatory | Mount Lemmon | — |
 Ultraviolet Explorer | — | — |
| Underwood observatory | Hubbardston | — |
| United States Naval Observatory Flagstaff Station | Flagstaff | 2.273 m |
| University Hills observatory | California | — |
 University of Alabama Observatory | Tuscaloosa | — |
| University of Central Arkansas Observatory | Conway | — |
| University of Maryland Observatory | Maryland | — |
| University of Minnesota observatory | Minneapolis | — |
| University of New Hampshire Observatory | Nuevo Hampshire | — |
| University of North Alabama Planetarium and Observatory | Alabama | — |
| University of North Dakota observatory | Grand Forks | — |
| University of Oklahoma Observatory | Oklahoma | — |
| University of Rhode Island observatory | Quonochontaug | — |
| USAF Academy Observatory | Colorado Springs | — |
| Vail View observatory | Vail | — |
| Van Allen Observatory | Iowa City | — |
| Vanderbilt Dyer Observatory | Tennessee | — |
| Veen Observatory | Míchigan | — |
| Vega–Bray Observatory | Benson | — |
| Venus Hill | Charlotte Amalie | — |
 VERITAS | Arizona | 1.268 m |
| Vermilion River Observatory | Illinois | — |
| Vermillion Cliffs observatory | Kanab | — |
| Vernonia Peak Observatory | — | — |
| Via Capote Sky observatory | Thousand Oaks | — |
| Vicksburg observatory | Vicksburg | — |
| Vulcan North, Lick observatory | Mount Hamilton (California) | — |
| Wallace Observatory | Westford | — |
| Wallis Observatory | California | — |
| Walnut Creek observatory | Walnut Creek | — |
| Waltonfields Observatory | Walton | — |
| Wanapum Dam observatory | Washington | — |
| Warner and Swasey Nassau Station | Chardon | — |
| Warner Observatory | Rochester | — |
| Warren & Beverly Observatory | Cloudcroft | — |
| Warren Rupp Observatory | Ohio | — |