Highway 26 was made into a Super-2 in the summer of 1997. It has three places where there are passing lanes. But 26 is a horrible highway, mostly because of the high traffic volume, numerous law enforcement officials, and the town of Rosendale. There is a 4-way stop at the intersection of 26 and Wisconsin 23, and it is terribly out of date. Many times I have been through there only to have a 2 mile backup. Plus the Rosendale police get their doughnut money from ticketing unsuspecting travelers. Anyway, if you are only taking this road to get from 41 to 151, the recommendation is to take 41 to 151 in Fond du Lac, it is only a few miles and minutes longer, and is well worth reducing the risk of a 20 minute backup or a speeding ticket.
On a brighter note, an interchange is being constructed in the summer of 1999 at the former intersection of US 41 and CTH N. CTH N will run underneath two new bridges on US 41. To construct this, WisDOT built a small bypass of the site on US 41 so that 4 lanes of traffic will be open at all times while the bridges are being built. I believe this interchange will be start of a conversion to freeway of US 41 between WI 26 and Fond du Lac. All that will need to be done to convert it after the new interchange is built will be to simply end roads that previously intersected with US 41.