River Severn | River Thames

The Mississippi River is the second longest river in the United States, with a length of 2,320 mi (3,734 km) from its source in Lake Itasca in Minnesota to its mouth in Gulf of Mexico. The longest is its tributary the Missouri River measuring 2,341 mi (3,767 km).

Further information

web.bryant.edu/~langlois/ecology/mississippihome.html

cgee.hamline.edu/rivers/Resources/river_profiles/mississippi.html