I went to college in Sioux County. Franken was born there, but now lives in Sioux City, which is extremely different from Sioux County. Even though it's not a big city by any stretch of the imagination, it is very city-like vs Sioux County. So his being a Dem is not all that shocking.
Also, partly due to the two liberal arts colleges in Sioux County, there is a very active Democratic party in the county, though I would say a majority are from elsewhere who have made the county their home for various reasons (not all are faculty), so a current Sioux County Democrat running for office wouldn't be completely unbelievable, either.
Do you think Franken could narrow the massive GOP edge in the area just a little bit?