Why was DuPage so conservative until 2008?

[King of Kensington]

When Barry Goldwater was bombing pretty much everywhere in the North, he easily won DuPage.

DuPage went GOP from 1852 until 2008 in every single election.

Why was it such a bastion of conservatism?

[TML]

This area was initially settled by Yankees (New Englanders) in the first half of the 19th century, and it voted for the Free Soil Party before the modern Republican Party was first established. It thus stuck with the Republican Party for over a century before the Republicans’ shift toward social conservatism along with the increased diversification of the county’s population eventually flipped it into the Democratic column by the late 2000s.

[President Punxsutawney Phil]

This area was initially settled by Yankees (New Englanders) in the first half of the 19th century, and it voted for the Free Soil Party before the modern Republican Party was first established. It thus stuck with the Republican Party for over a century before the Republicans’ shift toward social conservatism along with the increased diversification of the county’s population eventually flipped it into the Democratic column by the late 2000s.

DuPage County's record for voting Republican was one of the most consistent of any county-level jurisdiction in the United States. There are few places that voted for every single Republican nominee from John C. Fremont all the way to George W Bush.

[NorCalifornio]

DuPage has historically been a center of Evangelical Christianity, being home of both Wheaton College and the publishers of Christianity Today.

Combine that with its middle class/wealthy suburban character and its pre-suburbanization Yankee history, and the county's consistently GOP voting record through the 20th century makes a lot of sense.

[mileslunn]

GOP dominated suburbs for a long time and being above average income, fairly white and generally turned off by Chicago politics which Democrats dominated made it solid GOP.  Change recently happened for two reasons.

1.  Much more diverse as growing Hispanic and Asian community so its only around 75% white, not over 90% like past.

2.  Republicans there more old school style, not your modern populist/social conservative types so modern GOP is a bad fit for county.  Someone like John Kasich could probably win or at least come close there whereas Trump is a horrible fit for county. 

[jamestroll]

GOP dominated suburbs for a long time and being above average income, fairly white and generally turned off by Chicago politics which Democrats dominated made it solid GOP.  Change recently happened for two reasons.

1.  Much more diverse as growing Hispanic and Asian community so its only around 75% white, not over 90% like past.

2.  Republicans there more old school style, not your modern populist/social conservative types so modern GOP is a bad fit for county.  Someone like John Kasich could probably win or at least come close there whereas Trump is a horrible fit for county. 

Kasich would lose by at least 8 points there. lol rest of GOP is dead on arrival there.

And no, just because DeSantis won won Miami Dade and Palm Beach in November does not mean he will do significantly better in DuPage than Trump.

[Schiff for Senate]

This area was initially settled by Yankees (New Englanders) in the first half of the 19th century, and it voted for the Free Soil Party before the modern Republican Party was first established. It thus stuck with the Republican Party for over a century before the Republicans’ shift toward social conservatism along with the increased diversification of the county’s population eventually flipped it into the Democratic column by the late 2000s.

Interestingly, DuPage County in particular was a bastion for the religious right for a long time. As NorCalifornio said:

DuPage has historically been a center of Evangelical Christianity, being home of both Wheaton College and the publishers of Christianity Today.

[King of Kensington]

Suburban DuPage also elected Catholic pro-lifer Henry Hyde for many years.