| Thermopolis, Wyo., sale of hot springs by Eastern Shoshone and Northern Arapaho tribes | Encyclopedia | WyoHistory.org |
| Thomas, Oleta, oral history | Oral Histories | Casper College Western History Center |
| Thomas, Sarah, pioneer grave of | Encyclopedia | Randy Brown |
| Thomson, Thyra, Wyoming Secretary of State 1963-1987 | Oral Histories | Wyoming State Archives |
| Three Crossings, Oregon Trail landmark on the Sweetwater River | Encyclopedia | WyoHistory.org |
| Thuermer, Angus, Jackson Hole News editor | Encyclopedia | Kerry Drake |
| Tie Flume, Tongue River | Encyclopedia | Rebecca Hein |
| Tie Flume, Warm Spring Canyon | Encyclopedia | Robert and Elizabeth Rosenberg |
| Tie Hack Memorial | Field Trips | |
| Tongue River Tie Flume | Encyclopedia | Rebecca Hein |
| Tongue River Tie Flume remnants | Field Trips | |
| Toomey’s Mills | Encyclopedia | Nicole Lebsack, Stephanie Lowe |
| Toomey’s Mills/the Old Mill Inn | Field Trips | |
| Torrey, Col. Jay L. | Encyclopedia | Phil Roberts |
| Torrey’s Rough Riders | Encyclopedia | Phil Roberts |
| Trabing, August and Charles, freighters in Wyoming Territory | Encyclopedia | Nancy Trabing Mickelson |
| Trade, Native American pre-European contact | Encyclopedia | Samuel Western |
| Trail End State Historic Site | Encyclopedia | Cynde Georgen |
| Trail End State Historic Site | Field Trips | |
| Trails across Wyoming: The Oregon, Mormon Pioneer and California Routes | Encyclopedia | Terry A. Del Bene |
| Train wreck, Cole Creek | Encyclopedia | Lori Van Pelt |
| TransAmerica Trail | Field Trips | |
| Transcontinental motor convoy, 1919 | Encyclopedia | Lori Van Pelt |
| Trapper’s Point | Field Trips | |
| Treaties, Fort Bridger, 1863 and 1868 | Encyclopedia | WyoHistory.org |
| Tree Army, Wyoming | Encyclopedia | Kerry Drake |
| Tunison Lawsuit and Settlement | Encyclopedia | WyoHistory.org |
| U.S. Airmail in Wyoming | Encyclopedia | Steve Wolff |
| U.S. Bureau of Reclamation in Wyoming | Encyclopedia | Phil Roberts |
| U.S. Marines invade Teapot Dome | Encyclopedia | Carolynne Harris |
| Uinta County Courthouse | Field Trips | |
| Uinta County Museum | Field Trips | |
| Uinta County, Wyoming | Encyclopedia | Barbara Allen Bogart |
| Union Pacific Depot, Cheyenne | Field Trips | |
| Union Pacific Depots | Field Trips | |
| Union Pacific Ice Ponds | Field Trips | |
| Union Pacific in Wyoming, The | Encyclopedia | Gregory Nickerson |
| Union Pacific Roundhouse and Railyards Complex | Field Trips | |
| United Air Lines stewardess school, Cheyenne | Encyclopedia | Michael Kassel, Starley Talbott |
| United Airlines Flight 409, 1955 crash of | Encyclopedia | Thaddeus Mast |
| University of Wyoming Agricultural Experiment Station | Field Trips | |
| University of Wyoming Anthropology Department Museum | Field Trips | |
| University of Wyoming Athletics Hall of Fame | Field Trips | |
| University of Wyoming Geological Museum | Field Trips | |
| University of Wyoming Textbook Controversy | Encyclopedia | Phil Roberts |
| Unthank, Alvah grave, Oregon Trail site of | Encyclopedia | Randy Brown |
| Upton Chamber of Commerce | Field Trips | |
| Upton Old Town | Field Trips | |
| Upton, Wyoming | Encyclopedia | Nicole Lebsack |
| Uranium business, history of in Wyoming | Encyclopedia | Chamois L. Andersen, Lori Van Pelt |
