<Tr> <Td_colspan="2"> Discharge elsewhere (average) </Td> </Tr> <Tr> <Td> - Masontown, PA </Td> <Td> 8,433 cu ft / s (239 m / s) </Td> </Tr> <Tr> <Td_colspan="2"> Map of the Monongahela River basin, with the Monongahela River highlighted </Td> </Tr> <P> The Monongahela River (/ məˌnɒŋɡəˈhiːlə, - ˈheɪ - / mə - NONG - gə - HEE - lə, - HAY -)--often referred to locally as the Mon (/ ˈmɒn /)--is a 130 - mile - long (210 km) river on the Allegheny Plateau in north - central West Virginia and southwestern Pennsylvania, which flows from south to north . The Monongahela joins the Allegheny River to form the Ohio River at Pittsburgh . </P>

Where does the monongahela river start and end