A weather system could bring catastrophic flooding across four states, beginning on Wednesday amid rounds of heavy rainfall.

Rivers start in mountains, join other streams as they flow downhill, then channel into an open ocean or lake. Right? Well, ...

Rivers join downstream, flow downhill, and eventually meet an ocean or terminal lake: These are fundamental rules of how ...

Long before the Panama Canal, this historic trade route connected the Pacific and the Caribbean. Now you can follow the ...