The Main Street building represents the appearance of the towns along Highway 101 during the 1930s and 1940s and the businesses typically found there. Gas stations and and small businesses were important to the local economy. During Prohibition (1920-1933) people from the LA area traveling down the coast to Mexico for entertainment and booze would stop in the small towns along the coast on their way for food and gas. This introduced a lot of people to the area, some of whom would later become residents.

Exhibit speace within the Main Street building is used for rotating exhibits. The current exhibit is

Planting Paradise: Flowers, Farms and Families of San Dieguito 1920-2020.