Afton Trail Run Course Guide

Afton is regarded as one of the toughest trail races in Minnesota, and it earns that with repetition and heat rather than technical terrain. The 50K runs two 25K loops through Afton State Park, each with seven long climbs rising from the St. Croix River valley, for a total of 4,670 feet of gain. The race's own materials call it "a Hot Weather Race" outright: early July in Minnesota regularly hits highs in the mid-90s with heavy humidity, and the event has never been canceled or modified for heat. Running the same seven-hill loop twice, in rising heat, on a 9-hour clock, is what makes this a genuine test even though the course itself is not extreme on paper.

The official race guide lists 4,670 feet of elevation gain and 4,670 feet of loss for the 50K, a combined 9,340 feet of total elevation change across two 25K loops. Each loop has seven long climbs rising out of the river valley, with a good mix of rolling and flat terrain between them. Afton State Park sits on a glacial moraine scribed with deep ravines running down to the St. Croix River, and the vertical drop from the blufftop to the water is just over 300 feet, giving a sense of the terrain each of those seven climbs is cutting through.

Take the race at its own word here: Afton is explicitly billed as a hot weather race, with historical highs in the mid-90s and heavy humidity, though some years have run as cool as the low 70s. Aim for roughly 60 to 90 grams of carbohydrate per hour, and push sodium toward the upper end of the 300 to 700 milligram per liter range given the heat risk. The race orders 1,350 pounds of ice and 220 pounds of dry ice for cooling at aid stations and the finish, and runners are asked to carry a minimum of one water bottle at all times. Afton does not stock gels or sports drink, so bring your own and use your drop bag at the 25K/15.5-mile aid station. Build your numbers with the free ultra fueling calculator before race day.

The 50K carries a 9-hour time limit from the 6:30 a.m. start. The race also enforces a specific intermediate rule: sweeping and course teardown begins from the 25K aid station, which is the same as the start/finish area at the halfway point of the 50K, at 10:30 a.m. Any 50K runner not out of that aid station by 10:30 a.m. is pulled from the course. That gives you 4 hours to complete the first 25K loop, so a slow first loop directly threatens your ability to continue.

The 50K runs two loops of the same hilly 25K course, entirely off-road on minimum-maintenance gravel service roads plus double and single track through Afton State Park's trail system. Afton sits on a glacial moraine with deep ravines carved down to the St. Croix River, and sandstone outcrops are exposed in some of those ravines. Each loop climbs out of the river valley seven separate times, with rolling and flat terrain filling the gaps between climbs, and a vertical drop from blufftop to water just over 300 feet.

It is baked into the race's own planning, not incidental. Early July in Minnesota often brings highs in the mid-90s with high humidity, and in its history, the Afton Trail Run has never been canceled or modified for heat, only for severe weather like thunderstorms. The race compensates with 1,350 pounds of ice and 220 pounds of dry ice for aid station and finish-line cooling, and explicitly tells runners to train for and plan around hot, humid conditions rather than hope for a cool exception.