Not The Missouri, Not The Rio Grande: This Is North America's Largest River By Volume

When it comes to the largest bodies of water across the globe, there are more measurements than perhaps meet the eye. This is especially true for rivers. The 2,341-mile-long Missouri River is the longest in North America, followed by the Mississippi River at 2,320 miles. But when factoring in the average rate of flow (output) at the mouth, the Mississippi actually has the most volume. Due to these measurements, the Mississippi is North America's largest river.

Water movement is measured by cubic feet per second (cfs). The calculation reflects a volume of one cubic foot running through any given checkpoint during one second. One cubic foot per second equates to around 7.5 gallons flowing per second. The mouth of the Mississippi River is on Louisiana's Gulf Coast. Here, the river outputs a water volume of 593,000 cubic feet per second (via the U.S. Census Bureau, PDF).

When you do the math, it means the Mississippi River dumps out slightly under 4.5 million gallons of water into the ocean every second. Compare this to only 76,200 cfs (around 571,500 gallons) for the mouth of the Missouri River (via RiverSimulator.org, PDF) and that of the Rio Grande, the fourth longest river, clocking in at under 15,000 cfs.

As you can imagine, there are plenty of ways and places from which to enjoy this majestic waterway, especially if you enjoy river cruises. The Mississippi River Delta is where the river empties those millions of gallons into the ocean. The delta creates a unique ecosystem, blending fresh and salt water, which you can explore with Delta Discovery Tours. Trips with this ecologically-focused tour company leave just one hour from New Orleans in the small town of Empire, Louisiana. Choose from tours showcasing the region's dolphins, birds, or how industrial development affects the ecosystem.

Around 2,000 miles away at Minnesota's Itasca State Park, you can discover the birthplace of the Mississippi River, too. Aside from wading in the water right at the start of North America's largest river, you can check out the park's hiking trails or even book a campsite. 

Of course, there is more to experience than just the Mississippi River's beginning and end. Get to major points of interest in between with a river cruise. Although it's one of Europe's most popular cruise lines, Viking River Cruises is among the many cruise ship companies going up and down the Mississippi. Trip options with the Viking Mississippi include New Orleans, Memphis, St. Louis, and travel all the way to St. Paul.