Gwinnett County, Georgia

[Tintrlvr]

Absolutely a major factor, although the trend map by precinct also shows that heavily white areas closer to Dekalb County like Mountain Park (but not heavily white areas on the exurban fringe) were the areas that swung most strongly to Clinton. So it's a mix of demographic shifts and improvement for the Democrats among college-educated whites, and both factored into the large margin (although one or the other on its own might have been enough for the county to at least just barely flip).