Get ready to experience Boise's newest running celebration with The Boise Four, a series of four marathons and half marathons taking place throughout 2026 (starting May 2nd with The Boise River Marathon, followed by The Boise Marathon, The City of Trees Marathon, and The Boise Half Marathon). Whether you're just starting your running journey or you're a seasoned marathoner, you'll enjoy beautiful river views and tree-lined routes while earning exclusive series swag. Sign up by May 1st to lock in one flat rate for the entire series with your choice of distances—once the first race begins, this pricing option goes away!