It's called the Baja 500, Baja 1000, etc. I think that's as close as we're going to get.
Roads aren't the issue because much of the Dakar doesn't run on roads at all.
The problem with such an event across the SW is the presence of rangeland surrounded by tens of thousands of miles of barbed-wire fence. If it could be run on roads (it would have to), it would be an amazing feat, and if it could be pulled off, it would be awesome.
We do have things such as the Vegas to Reno Off-road races every year and back in 2000 there was the Nevada 2000 which was a 5 day lap of Nevada that started and ended in Las Vegas with stop overs each night in different towns with Reno as the main half way point. I ran the pit trailer for Team HUMMER from Reno on supporting 3 different trucks. If a person really wanted to try it most of the route could be used for a Rally with transits added in to by-pass the silt beds along the way. 'Best in the Desert" is the name of the group who puts it on along with a whole series of events, Ford puts up big money in several classes, something like $5000 for a win ib some classes with payouts down to 3rd along with year end awards.
Isn't there still a historic Rally from Mexico up through Nevada and on to Canada?
>>> which was stopped, in part, by eco-terrorists.
Definately terrorists. One of the races that I crewed during, I heard of at least two incidents involving piano wire stretched out between tunnel exits or yucca trees. I can't remember the details, but I recall one motorcycle rider was severly injured...
From the Sierra Club website, I guess someone forgot to read #4.
Our Mission Statement
1. Explore, enjoy and protect the wild places of the earth.
2. Practice and promote the responsible use of the earth's ecosystems and resources.
3. Educate and enlist humanity to protect and restore the quality of the natural and human environment.
4. Use all lawful means to carry out these objectives.
...in my humble opinion, the problem is "lack of organizers," and not so much a lack of roads but a lack of appropriate non-wilderness/protected terrain. A big part of Dakar is wandering around in the open desert.