| Lovell-Kane Area Museum | Field Trips | |
| Lucas, Frank | Encyclopedia | Wyoming State Archives |
| Lucy's Sheep Camp | Field Trips | |
| Lutheran missionaries | Encyclopedia | James H. Nottage |
| Lyman Heritage Barn | Field Trips | |
| Lynching of Edward Woodson, 1918 | Encyclopedia | Dick Blust, Jr. |
| Lynching of Wade Hampton, 1917 | Encyclopedia | Dick Blust, Jr. |
| MacKinnon, Anne, Casper Star-Tribune reporter and editor | Encyclopedia | Kerry Drake |
| Magill, Ada, Oregon Trail grave of | Encyclopedia | WyoHistory.org |
| Marbleton, Wyoming | Encyclopedia | Ann Chambers Noble |
| Martin, Joe, lynching of | Encyclopedia | Kim Viner |
| Martin’s Cove, events of 1856 | Encyclopedia | Annette Hein |
| Martin’s Cove, Mormon Church Acquisition of | Encyclopedia | Annette Hein |
| Mathew Campfield Park | Field Trips | |
| Matthew Shepard memorial bench | Field Trips | |
| Maynardier, Col. Henry E., Fort Laramie commander | Encyclopedia | Tom Rea |
| McCoy, Tim and Ed Farlow with Wind River Indians on stage and screen | Encyclopedia | Rebecca Hein |
| McCraken, Tracy, Cheyenne newspaper publisher | Encyclopedia | Kerry Drake |
| McGee, Gale, U.S. senator 1958-1976. | Encyclopedia | Rodger McDaniel |
| Mead, Elwood and Wyoming's water law | Encyclopedia | Anne MacKinnon |
| Medicine Bow Museum | Field Trips | |
| Medicine Bow Peak Plane Crash Memorial Plaque | Field Trips | |
| Medicine Bow Peak, plane crash into, 1955 | Encyclopedia | Thaddeus Mast |
| Medicine Lodge | Encyclopedia | WyomingHeritage.org |
| Medicine Lodge Archaeological Site | Field Trips | |
| Medicine Wheel | Field Trips | |
| Medicine Wheel | Encyclopedia | Fred Chapman |
| Meeks, Bub | Encyclopedia | Dick Blust, Jr. |
| Meeteetse | Field Trips | |
| Mercado, Felix on sugar-beet farming in the Big Horn Basin | Oral Histories | Washakie Museum and Cultural Center |
| Mercer, Asa Shinn, life and newspaper career of | Encyclopedia | Rebecca Hein |
| Metz, Percy, Big Horn Basin judge and trial lawyer | Encyclopedia | John W. Davis |
| Mexican Hill, Oregon-California Trail site | Encyclopedia | Randy Brown |
| Mexican Punitive Expedition, Wyoming National Guard and, 1916 | Encyclopedia | Carl V. Hallberg |
| Milholland, Inez, suffragist and orator | Encyclopedia | Lesley Wischmann |
| Military horses, Wyoming as breeding ground for, 1897-1949 | Encyclopedia | Rebecca Hein |
| Miller, Alfred Jacob, painter of the fur trade | Encyclopedia | Chavawn Kelley |
| Miller, Leslie | Encyclopedia | Wyoming State Archives |
| Mineral Leasing Act 1920 | Encyclopedia | Samuel Western |
| Mineral Leasing Act, 1970s amendments to | Encyclopedia | Samuel Western |
| Mineral Severance Tax | Encyclopedia | Sarah Gorin |
| Mineral Trust Fund, Permanent Wyoming | Encyclopedia | Sarah Gorin |
| Miss Indian America Pageant | Encyclopedia | Gregory Nickerson |
| Mission 66 in Yellowstone and Grand Teton Parks | Encyclopedia | John Clayton |
| Missionaries, German Lutheran | Encyclopedia | James H. Nottage |
| Mitchell Peak | Field Trips | |
| Mitchell, Finis, Wind River Mountains hiker and conservationist | Encyclopedia | Rebecca Hein |
| Mni Akuwin, Spotted Tail’s daughter | Encyclopedia | Tom Rea |
| Modernization in Wyoming’s national parks | Encyclopedia | John Clayton |
| Monumental Cemetery, Cremona, Italy | Field Trips | |
