Mazon River

{{Use American English|date=February 2025}}

{{Infobox river

| name = Mazon River

| image =

| image_caption =

| image_size =

| map =

| map_caption =

| source1_location = Greenfield Township, Grundy County, Illinois

| source1_coordinates= {{coord|41.183921|-88.2536703|region:US-IL|format=dms|name=Mazon River origin}}

| mouth_location = Confluence with the Illinois River, Morris, Illinois

| mouth_coordinates = {{coord|41.3530|-88.4198|region:US-IL|format=dms|name=Mazon River mouth|display=inline,title}}

| progression = Mazon River → Illinois → Mississippi → Gulf of Mexico

| source1_elevation =

| mouth_elevation = {{convert|489|ft|m|abbr=on}}

| length_mi = 28

| discharge1_location=Coal City, Illinois

| discharge1_avg = 373 cu/ft. per sec.{{Cite web|url=https://waterdata.usgs.gov/il/nwis/uv/?site_no=05542000&PARAmeter_cd=00065,00060|title = USGS Current Conditions for USGS 05542000 MAZON RIVER NEAR COAL CITY, IL}}

| custom_label = GNIS ID

| custom_data = {{GNIS 4|413173}}

}}

{{GeoGroup}}

The Mazon River or Mazon Creek ({{IPAc-en|m|ə|ˈ|z|ɒ|n}}), is a tributary of the Illinois River in the United States. The confluence is near Morris, Illinois.{{gnis|413173|Mazon River}}

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 {{convert|28|mi}} in length,U.S. Geological Survey. National Hydrography Dataset high-resolution flowline data. [http://viewer.nationalmap.gov/viewer/ The National Map] {{webarchive |url=https://web.archive.org/web/20120329155652/http://viewer.nationalmap.gov/viewer/ |date=2012-03-29 }}, accessed May 13, 2011 with the West Fork considered the main branch.

The river was named in honor of William Mason, a pioneer settler.{{cite book|last=Gannett|first=Henry|title=The Origin of Certain Place Names in the United States|url=https://archive.org/details/bub_gb_9V1IAAAAMAAJ|year=1905|publisher=U.S. Government Printing Office|page=[https://archive.org/details/bub_gb_9V1IAAAAMAAJ/page/n201 202]}}