City of Trees Marathon

The City of Trees Marathon is an annual road race through Boise, Idaho, run entirely on the Boise Greenbelt system along the Boise River. First held in 2002 and produced for two decades by the Ulmer family, the event is now organized by SoleKIDs, a local youth-focused nonprofit. The marathon starts and finishes near Parkcenter Park, heading west and north along the river for the first half before crossing near Bernadine Quinn Riverside Park and returning along the opposite bank. The course drops roughly 80 feet over the first six miles, then gradually regains that elevation on the return leg, making it a net-flat, out-and-back-style route shaded by cottonwoods along the river path. Race weekend also includes a Half Marathon, 10K, 5K, and a virtual option, with packet pickup at Shu's Idaho Running Company and a race-eve gathering at Payette Brewing. Held on a Sunday in mid-October, the event benefits from Boise's mild fall weather and gives finishers a certified marathon result on a course known more for its scenic river views than for crowd size.