The ninth longest river in the world is the Mekong, whose name begins with the letter M. It flows through Vietnam, Cambodia, Thailand, China, Laos and Myanmar. Its length is 4880 kilometers. The source is the Tibetan Plateau, which is located at an altitude of 5224 m above sea level, and the mouth is the South China Sea.
The Mississippi is a river beginning with the letter M. It is the second longest river in North America. It flows from the north to the south of the USA. The length of the Mississippi is 3,766 kilometers, making it the fourth longest river in the world. The Gulf of Mexico is the recipient of this river.