The North Branch Raritan River is a tributary of the Raritan River in central New Jersey. The North Branch Raritan River rises in Morris County, in eastern Mendham Borough rising out of Raritan Pond, and flows generally southward into Somerset County, around the southern end of the Watchung Mountains. At its end, it forms the border between Bridgewater and Branchburg Townships, and upon reaching the border of Hillsborough Township, joins the South Branch Raritan River to form the main Raritan River, which generally flows eastward from that point. This area where the branches converge was called "Tucca-Ramma-Hacking" by the Lenape, meaning the flowing together of water. It was called "Two Bridges" by the early European settlers, after a set of bridges built in 1733 that met at a small islan