Iditarod Trail Sled Dog Race early in the 20th century. The main route of the Iditarod trail extends from Seward in the south to Nome in the northwest, and was first surveyed by Walter Goodwin in 1908, and then cleared and marked by the Alaska Road Commission in 1911 and 1912. The entire network of branching paths covers a total of . Except for the start in Anchorage, the modern race follows parts of the historic trail. The trail is composed of two routes: a northern route, which is run on even-numbered years, and a southern route, which is run on odd-numbered years. Both follow
Iditarod Trail Sled Dog Race of those in the back of the pack. After Ophir, the trail diverges into a northern and a southern route, which rejoin at Kaltag. In "even"-numbered years ("e.g." 2016, 2018) the "northern" route is used; in "odd"-numbered years ("e.g." 2017, 2019) the "southern" route is used. During the first few Iditarods only the northern trail was used. In the late 1970s, the southern leg of the route was added. It gave the southern villages a chance to host the Iditarod race and also allowed the route to pass through the trail's namesake, the historical town of Iditarod. The two routes