The Hutchinson River is a freshwater stream located in Southern Westchester County, New York. The river forms in Scarsdale at Brookline Road and flows 10 miles (16 km) south until it empties into Eastchester Bay in the New York City borough of the Bronx. The river defines New Rochelle's jagged north-western city line, and serves as the boundary between New Rochelle and Scarsdale, New Rochelle and Eastchester, as well as Mount Vernon and Pelham.