In addition to the Orgyen Cho Dzong center you linked
to at http://www.tersar.org
there's also the NYC gompa which HH
Dudjom Rinpoche established and lived at named
Yeshe Nyingpo which is one of the current residences of his son Shenpen Dawa Rinpoche
who gives teachings and Wangs
there on occasion.
There's also Kundrolling, in NYC and Tselgyar East in Conway MA which are centers
of Namkhai Norbu: while he may not be precisely Nyingma
he teaches mostly Nyingma practices.
Between Dungse Thinley Norbu Rinpoche's center in upstate NY, Padmasambhava Buddhist Center, and HH Dudjom Rinpoche's own centers he established that Dungse Shenpen Dawa Rinpoche continues to uphold and expand according to his father's wishes the NY area is quite rich with Nyingma activity and we owe HH Dudjom
Rinpoche immense gratitude for that!