Apparently, according to Joshua Graham, it causes supply line issues. It will be more towards NCR-controlled area in that case. There may be NCR troops in the area (like how they are in the Mojave), but it is far from NCR territory.
I think Cheyenne Mountain would probably be inverted into Cheyenne Crater. It's a priority target anyway IRL in the event of nuclear war, and the plan for those targeting it is to just completely obliterate the mountain with multiple warheads.
So no, Cheyenne is undoubtedly not the location of the "Big Empty".
To the west, and a little north, of Primm there's a location called 'Canyon wreckage'. There's a bunch of Courier related graffiti there as well as one 'the Divide'. I'm guessing the wreckage will get cleared out and THAT'S where OWB will be.
Vegas is not all that far from Area 51. http://www.lasvegastourism.com/area_51.htm Also there is a link between the 2, there is a terminal just for workers of area 51 as well as a jumbo jet. So it is by no means contradictory at all, as Zion is further away from Vegas than A51. http://usparks.about.com/od/travelitineraries/tp/Driving-Distance-And-Drive-Times-From-Las-Vegas-To-Selected-National-Parks.htm Also Area 51 is not in any dlc, I asked and was answered during one of the q&a things for New Vegas. It svcks and is a major missed opportunity for them but whatever, they could be saving it.
"AREA 51, part of the Nellis Air Force Base is approximately 80 to 125 miles northwest of Las Vegas." I copied this out of that first area 51 site, and as far as Im concerned it seems like the perfect spot for the "Big Empty".
After few minutes search somewhere in Mojave Drive-in, I found real The Big Empty's enterance. The start location is not Mojave Outpost and either Mojave Drive in thru a crashes satelite.
It's from South East with unmarked map(In this case, no spoiler). Here is a hint, try think Northen Passage with block enterance.
We'll find out soon enough who is right, but guys, this had been discussed in multiple threads as recently as last week. This whole thread is just a rehash. The likely start point for OWB at the closed railway tunnel near the Mojave Drive-In has been discussed before, as one example.