Founded in 2013, the Mammoth Half Marathon is a premier race that celebrates the beauty and uniqueness of Mammoth Lakes while raising money to help its communities. As a nonprofit 501(c)(3), all net proceeds are donated to community service projects and local charitable causes. In addition, we hope to catalyze volunteerism as a way to help communities throughout Mammoth Lakes. The Mammoth Half Marathon is the second half of the “San Diego – Mammoth Challenge” and is the sister race to the San Diego Half Marathon held annually in March.