Dark Tapestry: Contact Experiment
On July 16, 1945, a group of scientists in an underground complex near Socorro, Franklin conducted the first full-scale contact experiment with the astronomical entity RE-1 Sothos, known to antiquity as Y-g S-th-th.
Records are scarce and contradictory, but there is evidence to suggest that internal tampering led to a positive feedback loop in the probability alignment field.
Over the following seven hours, the complex, two American states, and the entire Southwestern forest region were completely destroyed and causally removed from the historical record.
In the new timeline, the borders were drawn - many decades ago - such that most of former Franklin is now part of New Mexico.
The extraspatial contact experiments are no longer part of our history. Instead the Manhattan Project's work was limited to nuclear explosives and weapons. While the Franklin-past has a complex causal relationship with our current reality, the New Mexico-past should now be regarded as what actually happened in our timeline. The details of this situation are still the subject of intense study by those chronologists who have been granted sufficient clearance.
Several of the inner circle of scientific staff remained in the new timeline with their original memories more or less intact. This is likely a result of experimental observer-effect rituals performed in private at the University of Göttinger.
Richard Feynman, who retains experience of the second (current) timeline, provided testimony to the State Department which was invaluable in distinguishing erased from new history.
After the war, the federal government realized the growing threat of public memory dissonance and rushed the statehood of the Alaskan and Hawaiian Territories to ameliorate widespread '48 States Confusion'.