| Sublette County, Wyoming | Encyclopedia | Ann Chambers Noble |
| Suggs, Wyoming | Field Trips | |
| Sullivan, Mike | Encyclopedia | Wyoming State Archives |
| Sullivan, Mike, U.S. ambassador to Ireland, oral history | Oral Histories | Tom Rea |
| Swain, Louisa, first woman to vote under Wyoming Territory’s new woman suffrage law | Encyclopedia | Wyoming State Archives |
| Swan Land and Cattle Company | Encyclopedia | Rebecca Hein |
| Swan, Alexander | Encyclopedia | Rebecca Hein |
| Sweetwater County Historical Museum | Field Trips | |
| Sweetwater County, Wyoming | Encyclopedia | Dudley Gardner |
| T Cross Ranch | Encyclopedia | Stephanie Lowe |
| Table Rocks, Oregon Trail landmark | Encyclopedia | WyoHistory.org |
| Tarquinio, Enzo | Encyclopedia | Laura E. Ruberto |
| Tate Geological and Mineralogical Museum | Field Trips | |
| Tax, Mineral Severance | Encyclopedia | Sarah Gorin |
| Taylor Grazing Act, 1934 | Encyclopedia | Russel L. Tanner |
| Teapot Dome Scandal, The | Encyclopedia | Phil Roberts |
| Teapot Dome, Rocky Mountain Oilfield Testing Center and | Encyclopedia | Carolynne Harris |
| Teapot Dome, U.S. Marines and | Encyclopedia | Carolynne Harris |
| Ten Sleep | Field Trips | |
| Teno Roncalio Post Office Building | Field Trips | |
| Teton County, Wyoming | Encyclopedia | Clayton Caden, Shannon Sullivan |
| Teton Forest Reserve | Encyclopedia | John Clayton |
| Texas Trail Museum | Field Trips | |
| Thaxton, Edith, on Dances in the Bighorn Basin | Oral Histories | Washakie Museum and Cultural Center |
| Thayer, John | Encyclopedia | Wyoming State Archives |
| 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 G. and Elizabeth L. 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 |
