Why is Sangamon County, Illinois so Republican?

[Mr. Illini]

I have never been able to understand why the state government doesn't tip the county Dem more often. It makes up a huge chunk of the county's workforce, and I really do doubt that many of them are voting Republican regardless of their thoughts on Chicago.

[Mr. Illini]

Plus Peoria, Rockford, Champaign and the Quad Cities don't vote Republican.

3/4 you named are quite industrial and Champaign has a large university.

Rockford and Peoria BARELY voted for Hillary, and the surrounding counties that make up their metro areas voted very, very Republican (and usually do).  Champaign, while usually Democratic due to the U of I, is noticeably less Democratic than areas like Iowa City.  Rock Island County (Quad Cities), however, is pretty solidly Democratic.

Um...Peoria County went to Hillary. If Peoria BARELY went to her and the areas around it voted very, very Republican...