I am familiar with a lot of them, perhaps even a majority of them. But I have to confess, that before reading the list on the POTA Yahoo site, I wasn't even aware of Farny State Park, or Wawayanda State Park or even Double Trouble State Park (does that refer to Pennsylvania and New York? Sorry - no offense!). These and others I will have to Google for locations and directions.
In addition to these, there are also fourteen National Parks in New Jersey; but I believe that only twelve can be activated. I am pretty certain that bringing Amateur Radio equipment to Liberty Island and Ellis Island is not permitted.
Operating the parks and activating them seems to be a natural activity for someone who likes to QRP from the "Great Outdoors". If you're intrigued by this idea, I encourage you to visit:
72 de Larry W2LJ
QRP - When you care to send the very least!