What percentage of precipitation falling on the land becomes surface water, or runoff, and flows to the sea in river and stream channels?

What factors did the founders of your state use to determine the states boundaries ? did you states founders choose boundaries based on physical features or lines longitude and latitude ?

How did the movement of soldiers during world war 1 contribute to the global influenza (flu) pandemic of 1918 to 1919, which killed millions of people

How does central place theory explain patterns in the size and distribution of cities?