Mill B North Fork Trail does not get the same attention as the nearby Mill B South (Lake Blanche) hike but that is one of the things that make it great. While it does not have the iconic features of its sister trail, this hike should be considered on days when Blanche is extra crowded. This short but steep hike offers a small waterfall at the base of the trail near an abandoned mine. It is worth checking out if you have not seen them yet; they are located just past the wooden stairs that start the trail.
After you check out the waterfall and mine, proceed up the stairs and begin to take in the scenery of the Wasatch Mountains. The trail is a steady incline basically the whole way. Make your way through the pine forest and past the rock fins that jut out from the hillside. The view north shows the beautiful and rugged Mill B Fork of Big Cottonwood Canyon. As you near the top there is a trail that is easy to miss and that leads out to some amazing lookouts. While the small trail that heads off is not marked, it is fairly obvious where you will get the best views as you approach.
The trail continues further up the mountain, but make sure you take the time to go to the lookout. There are stunning views down onto Lake Blanche Trail, views down valley toward Salt Lake City, and views further up Big Cottonwood. The whole area is a plateau that allows you to explore more freely off trail, and there is a second peak that only requires some light scrambling to reach. Also, you will find some fire rings for backcountry campers in this area and atop the second peak.
Overall this is a relatively underused, quick, steep hike that has some of the best views in the canyon. Enjoy!