Why Do They Love Buicks So Much In Wisconsin?

I spent most of the last week in eastern Wisconsin, and it's got to be the Buick-est place in the country.

I don't think I've ever seen a Buick Rainier in California, but I saw five in one day between Oshkosh and Sturgeon Bay. Young people in Buicks. Families in Buicks. Beater Buicks. Nice Buicks. My question is: what does Wisconsin have in common with the world's other Buick epicenter, China?