Actually the test was closer Socorro and the small town of San Antonio, NM (birthplace of the Hilton dynasty.) It was on what is now White Sands Missile Range which is very close to Alamogordo, but there is a mountain range between the test site and Alamogordo. The blast was visible from San Antonio though.
I would add that Alamogordo was the fictitious location of the giant ants in the film "Them!"
http://en.wikipedia.org/wiki/Trinity_(nuclear_test)