This spot in Section 14, in the Town of Rietbrock, Marathon County is the exact center of the northern half of the Western Hemisphere. It is here that the 90th meridian of longitude bisects the 45th parallel of latitude, meaning it is exactly halfway between the North Pole and the Equator, and is a quarter of the way around the earth from Greenwich, England.
NOTE: You can see from the photos, that the marker is literally in the middle of cornfields. It will be on your right. I blew right past it because it was pretty well hidden in amongst the September-tall corn. If you're on Meridian Road and you come to the end of paved road and the beginning of a red dirt road, you've missed the marker. Turn around and head back towards County Road U; the marker will then be on your left.
Wikipedia: 45x90 Points
45x90 Club, Poniatowski, Wisconsin
Half Way to the North Pole and Half Way Around the Western Hemisphere
The Howder Family Blog: The 45x90 Spot