Dallas is the third-largest city in the U.S. state of Texas and the ninth-largest in the United States.
Dallas is historically significant because it is where American president John F. Kennedy was assassinated on November 22nd, 1963. The death of Kennedy has always remained a source of mystery and intrigue, in particular, the identities and motivations of those responsible for his murder. It is said that the very spirit of America was present that day to witness the fall of a president. 
One admittedly unreliable source has even suggested that the real President Kennedy had not even been on the planet Earth, let alone at Dealey Plaza in 1963. Instead, it has been posited that an alien doppelgänger took Kennedy's place on Earth while the real Kennedy went off to lead an alien revolution.  The death of Kennedy had such a far-reaching impact on society as a whole, that the day has been memorialized in a frozen pocket of null-time inside the Timepoint, as created by the villain known as Epoch.