The Allegheny River (/ˌæləˈɡeɪni/ AL-ə-GAY-nee) is a 325-mile (523 km) long headwater stream of the Ohio River in western Pennsylvania and New York, United States. The Allegheny River runs from its headwaters just below the middle of Pennsylvania's northern border northwesterly into New York then in a zigzag southwesterly across the border and through Western Pennsylvania to join the Monongahela River at the Forks of the Ohio on the "Point" of Point State Park in Downtown Pittsburgh, Pennsylvania. The Allegheny River is, by volume, the main headstream of both the Ohio and Mississippi Rivers. Historically, the Allegheny was considered to be the upper Ohio River by both Native Americans and European settlers.