The two branches meet at Hobart Gap near Interstate 78, continuing south through the Union County communities of Springfield, Union, Cranford and Clark. In Rahway the river receives the Robinson's Branch and South Branch, which are approximately long. The South Branch starts in Roosevelt Park in Edison behind the Menlo Park Mall, and flows through Edison, Iselin, and Rahway. The river's mouth is at the Arthur Kill between Carteret (on the south) and Linden (on the north), opposite Port Mobil on Staten Island.