Of course there are political factors. I have always heard that in Wisconsin many rural roads were paved to better serve dairy farmers beginning in the 1890s - and continued through the WPA program. While in Minnesota, similar rural roads remained unpaved.

Best link I could find to substantiate such a claim

https://www.uwlax.edu/currents/biking-in-the-driftless-regio....

Of course in contemporary times the high maintenance cost has many Wisconsin towns/counties considering returning to gravel.

https://www.wpr.org/economy/taxes/small-wisconsin-towns-pave...