I'm not sure. However, I would start with the following:
www.historicflemington.com, click "Commissions", click Historic Preservation
www.nps.gov/nr/ may be the best resource. it keeps a database.
Good luck,. And if you have any interest in buying or selling an historic home, that is my specialty.
I have personally bought and restored five historic properties, and helped numerous clients find their antique dream homes.
Best regards, Lynell Antonelli
Prudential Fox & Roach
Licensed in NJ & PA