In a 2001 interview with the Anchorage Daily News, Wilmarth said he saw the 1973 Iditarod as not really a sled dog race but more of a time to enjoy the Alaska wilderness with friends. He assembled a 12-dog team just a few months before the race, obtaining dogs from Native villages on the Kuskokwim River.
Thirty-five dog teams started the 1973 race and twenty-two finished. Competing in what would be his only Iditarod, Wilmarth won in a time of in 20 days, 49 minutes, 41 seconds, claiming the first-place prize money of $12,000. Almost two weeks behind him was John Schultz who became the recipient of the first ever "Red Lantern" award given to the last musher to cross the finish line.