In the early part of the 20th century, San Diego hosted two World's Fairs: the Panama-California Exposition in 1915 and the California Pacific International Exposition in 1935. Both expositions were held in Balboa Park, and many of the Spanish/Baroque-style buildings that were built for those expositions remain to this day as central features of the park. The buildings were intended to be temporary structures, but most remained in continuous use until they progressively fell into disrepair. Most were eventually rebuilt, using castings of the original façades to retain the architectural style. The menagerie of exotic animals featured at the 1915 exposition provided the basis for the San Diego Zoo. During the 1950s there was a citywide festival called Fiesta del Pacifico highlighting the area's Spanish and Mexican past. In the 2010s there was a proposal for a large-scale celebration of the 100th anniversary of Balboa Park, but the plans were abandoned when the organization tasked with putting on the celebration went out of business.

Answer this question, if possible (if impossible, reply "unanswerable"): What festival was celebrated in the 1950s in recognition of the city's Mexican and Spanish past?
Fiesta del Pacifico