The Soap Box Derby brought many thousands of people to Mission every year during its run and up to 20,000 at its peak. It began in 1946 after local business men and the Board of Trade decided to hold a Strawberry Festival in Mission. The goal was to provide funding for a much needed addition to the hospital after the war and to make Mission synonymous with strawberries. Jimmy Gunn, a committee member on the Board of Trade, thought of putting on a Soap Box Derby in conjunction with the Strawberry Festival. Both events were held on Main Street from Grand to Horne Street. Boys aged from 11 to 16 years of age were allowed to enter. In the following years the soap box cars had to be built to strict specifications by the boys, without receiving any outside help other than advice. The boys usually spent two to three months working on their cars, which were carefully inspected for safety and eligibility at each derby.

Mission's first derby in 1946 (a "wildcat" race) was a big success, and the following year, Mission's Soap Box Derby became a franchise of the American Soap Box Association. Becoming affiliated with the American Soapbox Association meant that the winner in Mission went to Akron, Ohio to race in the All-American Soapbox Derby Championship finals. In 1949, the increasing popularity of the derby caused it to remain on Main Street while the festivities of the Strawberry Festival were moved to the Fairgrounds (now the site of the Leisure Center).

By 1950, the derby was a province wide contest. Teams of volunteers and sponsors, including GM Motors and Shell Oil, all pooled their resources to ensure the event ran smoothly. In 1953, to accommodate the derby's increasing popularity, the city of Mission built a new track at the Fairgrounds to the same specifications as the track in Akron. Many considered the event a "character building experience" for the boys and the network of adults that supported them. The whole community that had worked diligently to make the derby a success was repeatedly praised by neighboring communities and beyond.

The derby's success surpassed everyone's expectations and in 1956 the Strawberry Festival was dropped to handle the derby exclusively. In 1958 the derby had over 200 contestants, representing over 40 different communities. However, the increasing number of entries and competition to build better cars contributed to decrease in local entries. The cost of staging the event had also increased with the rise in notoriety. Because income from the Strawberry Festival had offset a considerable part of the cost of staging such an enormous event, it was becoming more and more difficult to continue on revenues from the derby alone. Although the Soapbox Derby had a multitude of sponsors, they did not provide sufficient monetary contributions to offset the costs.

In the following years, the Soapbox Derby became more and more difficult to put on, due to a lack of funds and declining local interest. Eventually, GM Motors withdrew their sponsorship and the event was dropped in 1974.