Multiple realities
(covers information from several alternate timelines)

Dallas was a city in central Texas, Earth.

In an alternate timeline, set in 1944, after the Germans invaded the Atlantic coast of the United States, this city was in American territory. A major American military presence was located near this city. The name of this city and its location in Texas were displayed on a German map of the United States. (ENT: "Storm Front")

In 2328, Dallas was the point of embarkation for passengers traveling to Holberg 917G via commercial transport. Amanda Vackrinos, Kevin Ryan, and Paulina Ryan traveled there on the SS Kogin. (TNG-R: "Inheritance", okudagram)