Manassa’s most famous figure is heavyweight boxing champion Jack Dempsey, who left the community to make a life outside the San Luis Valley. He won the heavyweight championship in 1919, after knocking out Jesse Willard, but he lost it to Gene Tunney in 1926.

A museum in his honor, dedicated in Manassa in 1966, is housed in the cabin in which Dempsey was born. It contains several artifacts of Dempsey’s career, including the gloves he wore in the New York fight and numerous black-and-white photographs, which line the walls.​ The people in Manassa still celebrate his greatness, which stimulates them to succeed on their own in many professions, especially the medical.

This historic town was founded in 1878, after Mormon settlers arrived from the South, through Pueblo, fleeing persecution because of their faith. They also came from Utah and New Mexico, and they arrived near Los Cerritos, a settlement of Hispanics, who helped their Mormon neighbors survive a cold winter.

After Manassa was established, the Mormon faith helped the settlers survive throughout the years, and many expanded families lived in the town that is now the biggest community in Conejos County.

Manassa residents celebrate their foundation and their heritage every year on July 24, when they celebrate Pioneer Days.