A stream's watershed (also called its
basin or catchment) is the land
area that drains into that particular stream.
As your point of reference moves downstream,
the length of the stream and the watershed
feeding it grows in size.
As one stream joins another, the watershed
jumps in size as two watersheds are joined.
Thus a watershed grows to great proportions.
The watershed of the Mississippi River at its
mouth stretches from the ridge of the
Appalachians to the east slope of the Rockies.
It drains all or parts of 31 states and two
Canadian provinces-a total of 41 percent of the
continental United States.