No, the Mississippi River is not the longest river in the world; that title is a long-standing point of debate between the Nile in Africa and the Amazon in South America. Most traditional geographic records cite the Nile as the longest at approximately 6,650 kilometers (4,130 miles), though recent satellite studies in 2026 have argued that the Amazon is actually longer if you measure from its furthest Andean sources. The Mississippi River, when measured alone, is about 3,766 kilometers (2,340 miles), making it the second-longest river in North America. However, if you combine it with its primary tributary to create the Mississippi-Missouri-Jefferson river system, it reaches about 6,275 kilometers (3,900 miles), which places it as the fourth-longest river system in the world. While the Mississippi is a massive and culturally iconic waterway that drains 31 U.S. states and two Canadian provinces, it is significantly shorter than the "Big Two" of global river systems. It is, however, the "chief" river of the largest drainage basin in North America, making it a "heavyweight" in terms of volume and economic importance, even if it doesn't take the top spot for length.