High Quality Content by WIKIPEDIA articles! The Saddle River flows south through much of Bergen County, New Jersey. The river runs through densely populated suburban areas for much of its course. The headwaters of the Saddle River are in the piedmont terrain of Rockland County, in southern New York state. Streams from this area flow south, forming the Saddle River at their confluence, two miles south of the New York state border, in the town of Upper Saddle River, New Jersey.