The Mississippi River basin covers approximately one-third of the contiguous United States.

The Mississippi River basin covers roughly one-third of the contiguous United States, ranking it among the largest watersheds in North America. This expansive region spans portions of 32 states and affects a variety of ecosystems, agricultural practices, and industrial activities. The basin is vital for water drainage and sediment transport, influencing both natural environments and human endeavors. Its extensive scope underscores the river's importance in shaping the geography, economy, and ecology of the area.