The Divide

The Divide is what remains of Hopeville, an American military base. It lies in the vicinity of Death Valley in 2281.

Background
The Divide is a land torn apart by earthquakes and violent storms, it is suggested in dialogue with Johnson Nash that these storms are strong enough to skin people alive, where a major meteorological research project was undertaken by the company that owned the Big MT research station, somewhere near the small town of Hopeville. The project seemingly ended in catastrophe, later being said to have split the earth, destroying entire companies of NCR soldiers and cutting off supply lines along Death Valley Road and the Carson Pass Highway, granting Caesar's Legion time to recover after their loss in the First Battle of Hoover Dam.

There are rumors of survivors from the Divide, but these are viewed as legends, like the Sierra Madre, the Big Empty, and the Burned Man. In the future, the Divide is widely known to be the site of a decisive battle between the Courier and Ulysses. The battle is described as taking place beneath the "Old World flag", with each participant carrying a "message" for the other. The battle seems to become legendary, and word of it spreads far and wide.

Nothing is known about the current state of the Divide, except that it is partially inhabited, and that it contains undetonated warheads, most likely nuclear warheads within ICBMs (Intercontinental Ballistic Missiles), which would be safe in an isolated location which the area around Hopeville seems to be.

Appearances
The Divide is mentioned in Fallout: New Vegas, and all its add-ons (Dead Money, Honest Hearts, and Old World Blues) and its map is shown in Old World Blues. It appears in the add-on Lonesome Road.

Behind the scenes

 * In Fallout Tactics, the airship expedition of the Brotherhood of Steel is damaged crossing a "great divide", causing them to crash near Chicago and eventually create the Midwestern Brotherhood of Steel. It is highly probable that these two locations are the same.
 * Before the release of Lonesome Road, Chris Avellone's Twitter avatar showed the Divide.