The Missouri American Water MR340, commonly called the MR340, is a 340-mile nonstop paddling endurance race down the Missouri River from Kaw Point in Kansas City, Kansas, to St. Charles, Missouri. Founded in 2006, it has grown into one of the world’s longest and best-known nonstop river races.
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What makes the race distinctive
“Nonstop” means the clock keeps running day and night: racers decide when—or whether—to stop for food, rest, repairs, or sleep. Canoes, kayaks, stand-up paddleboards, and other human-powered craft tackle the river while ground crews often leapfrog downstream to resupply their racers; mandatory checkpoints and cutoff times keep the field moving toward the finish.
What makes the race distinctive
“Nonstop” means the clock keeps running day and night: racers decide when—or whether—to stop for food, rest, repairs, or sleep. Canoes, kayaks, stand-up paddleboards, and other human-powered craft tackle the river while ground crews often leapfrog downstream to resupply their racers; mandatory checkpoints and cutoff times keep the field moving toward the finish. MR340
The endurance challenge
The MR340 combines distance, sleep management, navigation, weather, nutrition, and river conditions rather than simply testing paddling speed. The official site describes an 85-hour limit, while elite crews can finish dramatically sooner; the 2026 edition demonstrated the difficulty, with 404 boats starting, 254 finishing, and 150 recording DNFs. MR340
A race built around the Missouri River
The event is hosted by Missouri River Relief, which had supported race safety for years before taking ownership in 2021. The race doubles as a fundraiser for the nonprofit and connects paddlers with communities along the river, making volunteers, checkpoint crews, safety boats, and racers’ ground crews unusually important parts of the event. Missouri River Relief
History and scale
The inaugural 2006 race was tiny—20 paddlers in 15 boats according to later race reporting—but the event now attracts hundreds of competitors. In 2026, the 21st running drew 623 paddlers from 37 states and three countries, including 312 first-time racers, illustrating how the MR340 has evolved from an extreme regional challenge into an international endurance-paddling event. Missourinet
Current status
The next scheduled running is the 22nd annual MR340, July 20–23, 2027, with July 19 mandatory check-in; August 17–20 is designated as the backup window if flooding or other safety concerns force postponement. Organizers deliberately target full-moon periods because so much of the race involves overnight paddling.