In the months following Pearl Harbor, an area of swampy land north of Portland, Oregon, was transformed into shipyard housing, and within six months, Vanport became the fifth-largest city in Oregon. But in 1948, the Columbia River levees burst, and the entire town was washed away. When the waters receded, only the streets of the town remained. Throughout the 1950s, these streets were known for clandestine racing. In the spring of 1961, the Portland Rose Festival Association and Cascade Sports Car Club decided to hold a sports car race on the old blacktop. The Rose Cup races established the viability of West Delta Park as a road racing circuit. Over time, the track was improved and extended by the local racing community, and its name soon changed to Portland International Raceway (PIR). What followed was the development of the only major road racing circuit located inside the borders of a major American city. Trans-Am, IMSA, CART, Champ Car, ALMS, and, of course, NASCAR have all raced at PIR, and the Rose Cup is going strong into its sixth decade.