The Denver Colfax Marathon: 2 days, 8 races. Includes Denver's only marathon! May 18-19, 2024 2 days, 8 races. Which will you choose? Denver's only marathon! To promote awareness and education of athletics, health and physical fitness among youth and adults, To raise funds and make contributions to schools and other charitable organizations, and to promote economic development of Col fax Avenue, to combat community deterioration, and to improve the vitality and safety of blighted urban neighborhoods throughout the three-city Colfax Avenue corridor