Before the Great War, this area was home to Hopeville and Ashton: a missile base and a large city located in the Mojave Desert in Southern California. Apart from being a major element of the ballistic defense matrix, Hopeville was also the subject of a major Big MT research project concerning meteorology; a project that apparently ended in a disaster, spawning the dust storms the Divide is infamous for. Besides the project, Big MT was also a partner in different enterprises: at one point, the entire local hippie commune that protested outside Hopeville against the ongoing Sino-American War were rounded up by special riot control officers, wearing a new model of L.A.P.D. riot armor, and shipped them off to Big MT as test subjects. The whole incident was regulated by the 11th Armored Cavalry Regiment who notably wore a recognizable helmet and a more advanced riot armor.
The Great War apparently surprised the soldiers, as the ICBMs there never left their missile silos. A silence fell across the land. For two centuries the soil of the Divide lay undisturbed by human presence. However, eventually, a small survivalist community established itself in the area. Kept alive by couriers, it prospered, and more settlers moved into the new city. It prospered enough in fact, to draw the attention of the New California Republic, who began to annex it swiftly for a newly established supply line across the treacherous Divide into the Mojave Wasteland.
These actions drew the attention of Caesar's Legion, which, in its bid to take the Mojave, attempted to cut the new supply line (the Long 15 and New Canaan were the two first), sending frumentarii and assassins to explore the area after a sizeable force of legionaries struck against the Republic's forces located there. But this war did not destroy the settlement. That was the work of the Courier, who, returning to the Divide again, carried a package from Navarro by order of the NCR, containing the activated ICBM detonator to the Divide, a short time before the NCR and the Legion jumped to each other's throat. When this device was close enough, it remote linked with the ICBM computers, sending a signal to the dormant nuclear missiles lying in the silos beneath the ground. They then began detonating one after another, splitting the earth, cracking and twisting the landscape, causing massive earthquakes. Entire companies of NCR soldiers in the Divide were trapped together with their Legion foes. The disaster created the Divide as it exists now: a wind-beaten maze of twisting canyons, skin-flaying dust storms and horrific abominations.
The Divide twisted the surviving NCR and Legion. As the winds flayed their skin and radiation ghoulified them, they became the marked men; skinless horrors fueled by hatred and rage for everything around them. Outside the Divide, the disaster became a blessing in disguise for the Legion: cutting off NCR supply lines along Death Valley Road and the Carson Pass Highway, it granted Caesar's Legion time to recover after their loss in the First Battle of Hoover Dam. However, it also gave birth to the greatest danger to the post-War civilization of the American Southwest: Ulysses. The Divide disaster both traumatized and inspired him as he learned the impact a single person, the Courier, can have on history.
At some point after the Divide disaster, the NCR sent an expeditionary force into the Divide. However, they severely underestimated the danger of the Divide and were met with heavy resistance. In the end, the expeditionary force was nearly wiped out by the Divide's many threats.
When ED-E passed through the Divide, computers remote scanned it then proceeded to make copies of it for maintenance purposes. Ulysses may have inserted the package into one in particular.
Ulysses was determined to take revenge and sought to reshape the post-apocalyptic world single handedly, much like the Courier reshaped the Divide by unleashing nuclear fire on it. At some point before the Second Battle of Hoover Dam, Ulysses contacts the Courier via a single message: the coordinates for the canyon wreckage west of Primm, and the words "Courier Six - Ulysses", wanting to destroy their new home in his reshaping process of America before their eyes, as the Courier did for him with the Divide. The Courier answered the call and confronted Ulysses at the Divide. There, under the Old World flag and the torn skies, the two decided the fate of America.