A single drop of rain, falling onto the roof of the Baseball Hall of Fame just above the bust of Mickey Mantle, will end up in the Chesapeake Bay.
That's how vast the Chesapeake Bay Watershed is.
For those who don't know the precise definition, a "watershed" can be visualized as the trough where a single drop of rain will travel (in theory). A tourist discarding a cigarette butt on the grounds of the Hall of Fame is harming the Chesapeake Bay Blue Crab.