This list covers 57 rivers whose names start with the letter M, ranging from “Mississippi” to “Mattole”. They range from major transboundary waterways that cross several countries to short coastal and tidal rivers that barely reach ten kilometers. Together they supply drinking water, irrigate farmland, power hydroelectric dams, and carry cargo and people across six continents.

Rivers are natural channels that carry water from higher ground down to a lake, sea, or ocean, shaped over thousands of years by the land they cross. Many have played a central role in human history, like the Moskva, which gave Moscow its name, or the Mekong, which still sustains one of the world’s largest inland fisheries. Beyond their practical uses, they often become defining features of the regions and cultures that grow up along their banks.

Below you’ll find the table with River, Countries, Length (km), Type, and Description.

River: the name of each river, so you can quickly find the one you’re looking for or compare it with others on the list.

Countries: the country or countries each river flows through, useful if you’re researching a specific region or border area.

Length (km): the river’s total length in kilometers, giving you a quick way to compare its size against the others.

Type: the kind of river it is, such as a major river, tributary, or transboundary river, helping you understand its role within a larger water system.

Description: a short summary of what makes the river notable, including its geography, history, or significance to the people who live nearby.

Rivers

RiverCountriesLength (km)Type
MississippiUnited States3,766Major river
MissouriUnited States3,767Major river
MekongChina, Myanmar, Laos, Thailand, Cambodia, Vietnam4,350Transboundary river
MurrayAustralia2,508Major river
MackenzieCanada1,738Major river
MagdalenaColombia1,528Major river
MarañónPeru1,600Headwater river
MadeiraBrazil, Bolivia3,250Major tributary
MamoréBolivia2,000Headwater river
MeuseFrance, Belgium, Netherlands950Transboundary river
MainGermany527Tributary river
MoselleFrance, Luxembourg, Germany544Tributary river
MurrumbidgeeAustralia1,485Tributary river
MacquarieAustralia950Tributary river
MurchisonAustralia780Ephemeral river
MahanadiIndia858Major river
MahaweliSri Lanka335Major river
MusiIndonesia750Major river
MahakamIndonesia980Major river
MunThailand700Tributary river
MeghnaBangladesh130Distributary river
MoulouyaMorocco600Major river
MaraKenya, Tanzania395Transboundary river
MangokyMadagascar564Major river
MaputoMozambique, South Africa, Eswatini380Transboundary river
MolopoSouth Africa, Botswana970Ephemeral river
MaricoSouth Africa, Botswana500Tributary river
ModderSouth Africa285Tributary river
MzimvubuSouth Africa220Coastal river
MetaColombia, Venezuela804Tributary river
MantaroPeru724Headwater river
MerseyEngland112Tidal river
MarneFrance514Tributary river
MureșRomania, Hungary761Tributary river
MiñoSpain, Portugal340Transboundary river
MoravaSerbia500Tributary river
MoskvaRussia502Tributary river
MotaguaGuatemala486Major river
MerrimackUnited States189Coastal river
MonongahelaUnited States209Tributary river
MohawkUnited States238Tributary river
MinnesotaUnited States534Tributary river
MilkUnited States, Canada1,173Tributary river
MercedUnited States233Tributary river
MooseCanada560Major river
MissinaibiCanada426Tributary river
MattagamiCanada443Tributary river
ManisteeUnited States304Major river
MuskegonUnited States349Major river
MenomineeUnited States, Canada187Border river
MilwaukeeUnited States166Urban river
MuskingumUnited States178Tributary river
MahoningUnited States178Tributary river
MaumeeUnited States220Tributary river
MiamiUnited States257Tributary river
MysticUnited States11Tidal river
MattoleUnited States100Coastal river

Descriptions

Mississippi
North America’s second-longest river, flowing from Minnesota to the Gulf of Mexico. It anchors the country’s inland shipping network and has shaped centuries of American history and culture.
Missouri
The longest river in North America, rising in Montana’s Rockies and joining the Mississippi near St. Louis. Lewis and Clark followed much of its course on their westward expedition.
Mekong
One of Asia’s great rivers, running from the Tibetan Plateau through six countries to Vietnam’s delta. It sustains one of the world’s largest inland fisheries.
Murray
Australia’s longest river, forming much of the border between New South Wales and Victoria and anchoring the country’s largest irrigation region, the Murray-Darling Basin.
Mackenzie
Canada’s longest river, draining Great Slave Lake north into the Arctic Ocean through the Northwest Territories. Its full watershed system stretches over 4,000 km.
Magdalena
Colombia’s principal river, running the length of the country between the Andes ranges to the Caribbean Sea, and long its main inland transport corridor.
Marañón
A major headwater source of the Amazon, rising in the Peruvian Andes and cutting through the dramatic Marañón Canyon before joining the Ucayali.
Madeira
The Amazon’s largest tributary by volume, formed from Bolivian headwaters. It ranks among the longest rivers in the world that aren’t a mainstem.
Mamoré
A broad Bolivian river that merges with the Beni to help form the Madeira, flowing through vast lowland wetlands rich in wildlife.
Meuse
Rising in France and crossing Belgium into the Netherlands, this historic river has seen centuries of European trade and conflict along its banks.
Main
Bavaria’s principal river and the Rhine’s longest tributary, flowing past Frankfurt before joining the Rhine at Mainz.
Moselle
Famous for the vineyards lining its banks, this scenic river flows from France through Luxembourg into Germany, meeting the Rhine at Koblenz.
Murrumbidgee
A major tributary of the Murray River, winding through New South Wales and supporting the irrigated farmland of the Riverina region.
Macquarie
Flowing through central New South Wales into the Darling-Barwon system, its wetlands at the Macquarie Marshes are an important wildlife refuge.
Murchison
A largely dry riverbed for most of the year in Western Australia, filling dramatically after seasonal rains before reaching the Indian Ocean.
Mahanadi
One of eastern India’s largest rivers, flowing through Chhattisgarh and Odisha to the Bay of Bengal and supporting major irrigation and hydropower.
Mahaweli
Sri Lanka’s longest river, rising in the central highlands near Adam’s Peak and irrigating the island’s ancient agricultural heartland.
Musi
Sumatra’s largest river, flowing through Palembang to the Bangka Strait and historically central to the ancient Srivijaya trading kingdom.
Mahakam
East Kalimantan’s principal waterway on Borneo, home to a rare population of freshwater Irrawaddy dolphins in its middle reaches.
Mun
Thailand’s longest river entirely within its own borders, draining the Isaan region before joining the Mekong near the Cambodian border.
Meghna
Formed where the combined Ganges and Brahmaputra waters converge, this wide river carries an enormous volume into the Bay of Bengal.
Moulouya
Morocco’s longest river, running from the Atlas Mountains northeast to the Mediterranean Sea near the Algerian border.
Mara
Famous for the wildebeest migration crossings, this river flows from Kenya’s highlands through the Serengeti-Mara ecosystem into Lake Victoria.
Mangoky
One of Madagascar’s largest rivers, draining the island’s western highlands through a wide delta into the Mozambique Channel.
Maputo
Flowing through three countries before reaching the Indian Ocean, this river gave its name to Mozambique’s capital city.
Molopo
Marking part of the border between South Africa and Botswana, this river runs dry for most of the year along the Kalahari’s fringe.
Marico
A tributary of the Limpopo forming another stretch of the South Africa-Botswana border, known for its clear spring-fed pools.
Modder
A Free State river feeding into the Riet and eventually the Orange River system, important for local farming and Bloemfontein’s water supply.
Mzimvubu
The Eastern Cape’s largest undammed river, cutting a dramatic gorge near Port St Johns before meeting the Indian Ocean.
Meta
A major tributary of the Orinoco, forming part of the Colombia-Venezuela border as it crosses the eastern plains, or Llanos.
Mantaro
Part of the Amazon’s ultimate source system in Peru’s central Andes, feeding hydroelectric dams that supply much of the country’s power.
Mersey
A short but historically vital river whose estuary made Liverpool one of the world’s great trading ports during the industrial era.
Marne
Flowing through the Champagne region into the Seine near Paris, it gave its name to decisive First World War battles fought along its banks.
Mureș
Rising in Romania’s Carpathians and crossing into Hungary, it’s one of the Tisza’s main tributaries and Romania’s longest internal river.
Miño
Galicia’s longest river, forming the border between Spain and Portugal along its lower course before reaching the Atlantic.
Morava
Formed by the union of the South and West Morava, Serbia’s longest internal river flows north to join the Danube.
Moskva
The river that gave Moscow its name, winding through the capital before joining the Oka, itself a tributary of the Volga.
Motagua
Guatemala’s principal river, running from the highlands to the Caribbean and marking the source of the country’s famous jade deposits.
Merrimack
Flowing from New Hampshire through Massachusetts to the Atlantic, its water power fueled the region’s 19th-century textile mill boom.
Monongahela
Joining the Allegheny at Pittsburgh to form the Ohio River, it was historically vital for moving coal and steel.
Mohawk
New York’s major Hudson tributary, whose valley became a key westward route and later the path of the Erie Canal.
Minnesota
Flowing from the South Dakota border across southern Minnesota to join the Mississippi near the Twin Cities.
Milk
Winding across the Montana-Alberta-Saskatchewan borderlands before joining the Missouri, named for its pale, milky-looking water.
Merced
Draining Yosemite Valley’s granite cliffs and waterfalls before flowing into the San Joaquin River in California’s Central Valley.
Moose
Draining a large part of northern Ontario into James Bay, formed by the union of the Mattagami and Missinaibi rivers.
Missinaibi
One of Ontario’s longest free-flowing rivers, a popular wilderness canoe route that feeds into the Moose River.
Mattagami
A northern Ontario river that joins the Missinaibi to form the Moose River, its watershed dotted with hydroelectric dams.
Manistee
A scenic northern Michigan river popular for canoeing and trout fishing, flowing west into Lake Michigan.
Muskegon
Draining a large stretch of central Michigan into Lake Michigan, historically central to the state’s lumber industry.
Menominee
Forming part of the Michigan-Wisconsin border, its lower falls once powered one of the country’s biggest lumber ports.
Milwaukee
Flowing through downtown Milwaukee into Lake Michigan, joined near its mouth by the Menomonee and Kinnickinnic rivers.
Muskingum
Ohio’s largest wholly-contained river, flowing into the Ohio River and historically improved with locks for early river commerce.
Mahoning
Flowing through Ohio’s industrial Mahoning Valley, once lined with steel mills, before joining the Beaver River in Pennsylvania.
Maumee
Flowing through Ohio and Indiana into Lake Erie at Toledo, draining one of the Great Lakes’ largest watersheds.
Miami
Also called the Great Miami, it flows across southwestern Ohio into the Ohio River, distinct from Florida’s better-known city of the same name.
Mystic
A short tidal river through the northern suburbs of Boston that empties into Boston Harbor.
Mattole
A remote Northern California river prized by conservationists for its wild salmon and steelhead runs through the Lost Coast region.
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