Rivers of the World

I remember learning a few things in High School- not all that many but a few. One was from Geography class. We learned about what I thought were just two rivers in Pittsburgh: The Allegheny and Monongahela. 
  Well , I was wrong . There are actually three rivers involved here. The Allegheny and Monongahela come together to form the Ohio River. 
  Most rivers start in mountainous terrain, as fresh and quickly moving streams. The Allegheny, which is 325 miles long, starts in north central Pennsylvania, Porter County, and moves north into New York, then back into Pennsylvania. Allegheny is American Indian(don't remember which tribe)for "fine river". 
  The Monongahela, which is 128 miles long, originates in Freemont, West Virginia and moves its way due north. It's one of the few navigable north-south rivers. The name again is from the American Indians and means "high bluffs". 
  These two converge in downtown Pittsburgh to form the Ohio River. It's 981 miles long and ends in Cairo, Illinois where it meets the mighty Mississippi. Can't help but think of Mark Twain here.
  The Mississippi River is the longest in North America, spanning from someplace in Minnesota(I should know that, I guess) all the way to the Mississippi Delta, touching on 10 states in the process. It's what the Aorta is to the body. With its various tributaries- the Ohio, the Arkansas, Tennessee and Missouri rivers to name a few- it affects 31 of the United States. 
   Across the pond, one river I didn't know about until recently(good old Jeopardy!)was the Mekong. It's the longest river in southeast Asia, spanning six countries. The point of origin is Quinhang province in China, where it drops to the Yunnan province, and then Myanmar, Thailand, Laos, Vietnam and Cambodia before emptying into the South China Sea. It makes me think of the Mississippi(minus the Mark Twain imagery)in that it covers the entire length of southeast Asia before spilling out in the drink. 
  The longest river in the world is of course the Nile, spanning much of Africa from east to west, draining finally in the Mediterranean. Next up by a small margin is the Amazon in South America. Other main rivers are the Danube, the Volga, the Yangtze and Yellow rivers, and the Ganges, Tigris and Euphrates.
   Rivers start out as pure water and gradually accumulate saltiness from the minerals in the rocks and soil they pass over. The point at which they meet a larger body of water(which is considerably saltier) is called the Estuary, where the two waters converge. Usually called Gulf or Bay or Sound.  
   Okay, we're reaching the end of my knowledge on this subject. Hope it was entertaining, maybe even mildly educational. Next up- God only knows..