squeak-
I did a bit of research (google = research), and it seems that the WTC had two zip codes, but each tower didn’t have two.
According to ChaCha, “The Empire State Building is the only building in New York City to have its own zip code. It’s 10118.”
As per Wikipedia:
There are four types of ZIP codes: Unique (assigned to a single high-volume address), P.O.-box-only (used only for P.O. boxes at a given facility, not for any other type of delivery), Military (used to route mail for the U.S. military) and Standard (all other ZIP codes). As examples of Unique ZIP codes, certain governmental agencies, universities, businesses or buildings that receive extremely high volumes of mail have their own ZIP codes, such as 20505 for the Central Intelligence Agency in Washington, D.C., 81009 for the Federal Citizen Information Center of the U.S. General Services Administration (GSA) in Pueblo, Colorado; 30385 for BellSouth in Atlanta; and 21412 for Bancroft Hall, the midshipman dormitory at the United States Naval Academy. An example of a P.O.-box-only ZIP code is 22313, which is used for P.O. boxes at the main post office in Alexandria, Virginia, as well as for the United States Patent and Trademark Office. In the area surrounding that post office, home and business mail delivery addresses use ZIP code 22314, which is thus a Standard ZIP code.
Sometimes zip codes are retired. An example is the town of Halcott Center in Greene County, NY, whose 12437 zip code was eliminated (it joined the 12430 area).
Much of the NY Catskill area is less populated than it was half a century ago, and several towns have disappeared under reservoirs that were built for NYC’s water supply – Union Grove, Neversink, Shavertown, and others. (For some reason, the thought of those old towns buried underwater gives me the creeps – those who were born and grew up there truly can’t go home again.)