From the beginning of the Republican Party, the pattern was clear: the Republicans were solid in Northern Illinois, the Dems were solid in Southern Illinois:
It was even true in 1984:
By 2000, the pattern was shifting:
By 2004, the pattern was solidifying:
And in 2008, a handful of northern Illinois counties voted Democratic for the very first time in their post-1852 history -and none of the six counties that voted strongest for Fremont in Illinois voted for McSame at all:
And when the Rmoney wave came, it came back from the South. Only three of the six most Fremont-voting counties in Illinois came back into the Republican fold -the same number that voted for Goldwater in 1964, a much worse year for the GOP:
A bunch of southern Illinois counties went more heavily for Rmoney 2012 than for Bush 2004. A bunch of northern Illinois counties that went for Bush both times went for Obama both times.
The presidential candidate in 2016 who most closely conformed to early Republican voting patterns was Kasich: the candidate Republicans who live around rich Democrats vote for.
Kasich was strongest in Illinois in DuPage county, the second-most populated county in Illinois. It experienced almost no population growth in the 2000s, but it swung more than 10 points from Bush 2004 to Obama 2008, thus voting for the Democratic presidential candidate for the first time in its post-1852 history in 2008. In 2012, it voted for the Democratic candidate for President again, by a margin a little smaller than the national average.
In the 2016 primaries, the candidate who won the most votes in DuPage county was Bernie Sanders, followed by Clinton, Trump, Kasich, Cruz, and Rubio.
The facts are clear: the Yanks are shifting not just more Democratic, but more liberal. The Border Reviers are shifting more Republican and possibly even more conservative. Who the heck could possibly vote both for Barry Goldwater and Barack Obama? The two are ideological polar opposites.
Southern Illinois, which went heavy for LBJ, is gonna go heavy for Trump.