title: Mazon River
text: # Mazon River
  
  The Mazon River or Mazon Creek (/məˈzɒn/), is a tributary of the Illinois River in the United States. The confluence is near Morris, Illinois.
  
  The Mazon River is associated with the Mazon Creek fossils of the Francis Creek Shale, which are also exposed in strip mines and quarries near the River. This fossil bed includes well-preserved fossils from the Pennsylvanian period of the Paleozoic era and is a world-famous Lagerstätten site.
  
  The Mazon River is approximately 28 miles (45 km) in length, with the West Fork considered the main branch.
  
  The river was named in honor of William Mason, a pioneer settler.
  
  ## Cities and counties
  
  The following cities, towns and villages are within the Mazon watershed:
  
  * Braidwood
  * Coal City
  * Dwight
  * Gardner
  * Mazon
  * Morris
  
  The following counties are at least partly drained by the Mazon River:
  
  * Grundy County
  * Kankakee County
  * Livingston County
  * Will County
  