"Does the sun just shine less brightly in Minnesota"?
This is a good question, and an often misunderstood one. Yes, where you live the sun is different than other places. We moved to Florida recently from New Mexico, and the sun is very different out here, something I expected since I've lived all over the country. There's sun, and there's sun. On a bright New Mexico day at noon, it was more like sunny f16 or even f22! Portland, Oregon was very different than NM. That's probably the most extreme difference I've seen, and as charjohncarter said, the sun is different from season the season, time of day, etc. Sunny 16, or 8 in your case, is a rough estimate that's "good enough" because print film has such a wonderful exposure latitude. Just take a camera w/ a spot meter out sometime and see how it meters all over the place in even slightly different street scenes.
I used to worry about this. When going out w/ my N90s and spot metering that meter readout was amazingly busy in the viewfinder, whereas my handheld meter held pretty steady. But when I went w/ one or the other, the shots were nearly always exposed just fine. Tri-X and good development seemed to make everything all right in the end.