The Mississippi River Watershed includes the Missouri and Ohio Rivers, and 59% of all US rivers, draining parts or all of 32 states.[1] It is really an astoundingly massive river system, which is why it is the fourth largest in the world.

[1] https://assets.bwbx.io/images/users/iqjWHBFdfxIU/i9QxpflmIAz...