Editing Champaign County, Illinois (section)

==Geography==
The county is 27 miles wide (east–west) and 36 miles long (north–south).<ref>{{cite book |last1=Hopkins |first1=Cyril G. |last2=Mosier |first2=J. G. |last3=van Alstine |first3=E. |last4=Garrett |first4=P. W. |title=Champaign County soils |date=1918 |publisher=University of Illinois Agricultural Experiment Station |page=1 |url=https://books.google.com/books?id=UDK8TNij-tkC}}</ref> Its area is {{convert|998|sqmi}}, of which {{convert|996|sqmi}} is land and {{convert|2.1|sqmi}} (0.2%) is water.<ref name="census-density" /> It is the fifth-largest county in Illinois by land area.

Because Champaign County is situated on a large and very flat [[plateau]], it had virtually no natural drainage, so that much of the County consisted of wetlands until drainage ditches were built, beginning in the 1870s. This was an example of an upland [[marsh]], which resulted in a high incidence of [[malaria]] before the late nineteenth century.

The topography of Champaign County was formed by the [[Wisconsin glaciation]] about 20,000 years before the present. Lobes of ice from what is now [[Lake Michigan]] crossed the county, creating a deep pile of glacial soil, up to 300 feet thick, topped by numerous [[moraine]]s forming small, flat watersheds with no outlets.

Champaign County is situated on the [[Drainage divide|divide]] between the [[Ohio River|Ohio]] and [[Mississippi River]]s. Rivers flow out of Champaign County to the east, west, and south. The [[Kaskaskia River]] has its origin to the northwest of [[Champaign, Illinois|Champaign]], draining the western side of that City. The Kaskaskia flows toward the southwest, joining the [[Mississippi River|Mississippi]] south of [[St. Louis]], [[Missouri]].

The [[Embarras River (Illinois)|Embarras River]], on the other hand, drains the south-central portion of [[Champaign–Urbana metropolitan area|Champaign–Urbana]], originating in southeastern Champaign and flowing through the experimental fields on the southern part of the campus of the [[University of Illinois Urbana-Champaign|University of Illinois]]. The {{not a typo|Embarras}} is a tributary to the [[Wabash River]] and [[Ohio River]] systems. The northeast corner of Champaign, the central portion of the University campus, and the northern part of Urbana are drained by the [[Boneyard Creek]], which flows into the [[Saline Branch]], a tributary of the [[Vermilion River (Wabash River tributary)|Vermilion]] and [[Wabash River|Wabash]] rivers.
[[File:Champaign County Courthouse.jpg|right|thumb|Champaign County Courthouse in Urbana]]

===Adjacent counties===
* [[McLean County, Illinois|McLean County]] – northwest
* [[Ford County, Illinois|Ford County]] – north
* [[Vermilion County, Illinois|Vermilion County]] – east
* [[Edgar County, Illinois|Edgar County]] – southeast
* [[Douglas County, Illinois|Douglas County]] – south
* [[Piatt County, Illinois|Piatt County]] – west