Bruce "Buck" Nelson appears to be the only person to thru-hike the entire Desert Trail, 132d0h25m from Mexico to Canada, March 1 - July 11, 2012.
Nelson hiked the then-designated route, then continued on via a route of his own design through Oregon, Washington and Idaho, to the border with Canada, a total of 2223 miles. Nelson pre-set dozens of food and water caches for the first 1000 miles, returned (by car) to the Mexico border to retrieve the caches, then laid out 20 more caches in northern Nevada and part of Oregon.
Nelson provided the following useful links about his hike and the Desert Trail:
bucktrack.com/Desert_Trail_Thru-Hike.html (Introduction with some historical info on the route)
bucktrack.com/The_Desert_Trail_Map.html (Map)
postholer.com/Colter (Journal)
bucktrack.com/Desert_Trail_Guide_Books.html (Guide Books)
bucktrack.com/Desert_Trail_Gear_List.html (Gear List)
The route is mostly cross country walking through desert, washes, across dry lake beds and along ridge lines. In places the route follows wild horse and burro trails and 4WD trails. In some places the route follows gravel roads. Most “road-walking” is in places where vehicles are rarely seen... Obviously hiking over 2,000 miles is considerable work any way you cut it, but although there are hundreds of miles of cross-country travel most of it is fairly easy going and there is less climbing than on any of the well-known “Triple Crown” trails. - Buck Nelson
This is a record that can be rather "easily" broken by an experienced hiker in good shape. - Buck Nelson