In 1932, Zoo Idaho opened at a local trailer park with just two animals on display in wire pens: a female rhesus monkey named Josephine and a raccoon named Pete. Twelve-year-old John Marshall had caught the raccoon under the Portneuf River bridge and proudly donated him to the new zoo. Twice a month in the spring and summer, John and his grandfather William Raymond, superintendent of the Park Department, would take Pete on a collar to catch crawdads, snails, and pollywogs in the river. In the winter, the monkey was kept in John’s garage, heated by three 300-watt bulbs and an electric heater.

In the early 1930s, Governor C. Ben Ross—a former Pocatello mayor—appropriated funds for the purchase of land to create a park in Pocatello. Raymond and the City Council decided on a site in South Pocatello characterized by natural lava rock and sagebrush, which soon became home to Zoo Idaho and was given the name Ross Park after the governor.