First, New York and the rest of the Northeast have been the last region the Mexicans have moved into simply because of geographic distance.
Second, the Mexicans face more competition from other groups in New York City than pretty much anywhere else in the country. There you not only have the Colombians and Dominicans, you also have Cubans, Jamaicans, Asians, as well as the Italians and others.
On a side note, somebody's knowledge based on simply living in an area only goes so far. One's zip code doesn't automatically afford them special insight on things. I can learn more from just reading the latest Drug Threat Assessment from the DEAD or HIDTA report than reading posts from a dozen New York posters on the boards.
Mods should mind their own business and leave poster's profile signatures alone.