| Marys River | |
| Source1 Coordinates: | 38.1853°N -89.6279°W |
| Mouth Location: | Confluence with the Mississippi River |
| Mouth Coordinates: | 37.8803°N -89.7832°W |
| Mouth Elevation: | 354feet |
| Length: | 41miles |
| Custom Label: | GNIS ID |
Marys River is a tributary of the Mississippi River in Illinois. It drains a small watershed between the Big Muddy River and the Kaskaskia River. It joins the Mississippi just southeast of Chester, near Kaskaskia. Because of its proximity to Kaskaskia — the capital of Illinois Territory and the first capital of the State of Illinois — Marys River was the site of early settlements leading into the interior of Illinois.
Marys River is approximately in length.[1]
The following cities and towns are in the Marys River basin:
Parts of the following counties are in the Mary's River basin: