Watersheds famously …
Don’t obey jurisdictional lines.
Major Rivers and Watersheds of the United States
The reason? For one, most (or many) jurisdictional lines are straight whereas watersheds and rivers — at least in their natural state — abhor straight lines. Many a squiggly state line actually follow along the path of a river. The top of Kentucky, the bottom of Indiana and Ohio and the side of West Virginia are each formed by the Ohio River. Probably most famous in that regard is the southern boundary of Texas, as delineated by the Rio Grande. Mexico and Texas aren’t so much separated by the river as they are united by the Rio Grande Watershed (orange). The same principle applies on the northern boundary with the Red River. It flows north into Lake Winnepeg which is part of the larger Saskatchewan Basin that flows into St. James Bay.
Morale of the Story: Rivers and watersheds go hand in hand, and yes, they will cross over jurisdictional lines.