What I find kind of funny is that in, say, New York, it looks like Republicans had support in the rural areas while Democrats had support in New York City. However in Illinois, Republicans had support in Chicago, but downstate in the more rural areas was McClellan territory.
I think that has to do with Irish Catholic immigrants in NYC who were strongly Democratic (and anti-war, remember the draft riots) vs WASPs in Upstate NY, compared to German immigrants in Chicago who were strongly Republican vs people descended from Southerners and more culturally close to the South than anywhere else in the North in Downstate Illinois. In other words, the divides were cultural and ethnic, not urban vs rural.
