December ultramarathons in Wisconsin, United States

Rugged winter ultramarathon with 136 feet elevation gain per mile, persistent climbs and descents at Twin Valley's chilly, scenic terrain

Out-and-back 50K on the Glacial Drumlin State Trail from Lake Mills to Cottage Grove, a steady rail-trail route with a peaceful overnight feel.

Rolling hills, mixed trail and gravel with mostly asphalt, northwestern Wisconsin scenery, potential winter conditions in December