The road course is almost perfectly flat and runs clockwise. Two track configurations are possible. One includes a hard chicane at the end of the front straight and involves 12 turns at length of 1.967 miles (3.17 km). Without the chicane, the track has nine turns and a lap length of 1.915 miles (3.08 km).
PIR is built on the former location of Vanport, Oregon, which was destroyed on Memorial Day, May 30, 1948, when a dike on the Columbia River broke and flooded the city. After the flood, all that remained were the paved streets and concrete foundations of destroyed buildings.
The first races took place on these old city streets in 1961 during the Portland Rose Festival. Since then, the Rose Cup has become an annual event. Racing at "West Delta Park", as PIR was known back then, was quite dangerous. Racers leaving the track unexpectedly could collide with leftover concrete foundations or fall into ponds.
Under the threat of losing the Rose Cup races, since many of the sanctioning racing bodies would no longer sanction races due to the deteriorating roads and dangerous obstacles, the track was finally paved in the 1970s.
In 1999 and 2000, the NASCARCamping World Truck Series ran a race at Portland International Raceway. The race was added after the demise of the ½-mile Portland Speedway that hosted races early in the series.
At the end of 2007 and the beginning of 2008, PIR went through a track renovation. The track was repaved with new asphalt and some minor changes were made to the track layout. Turns 4-7 were widened. The fence on the inside of turn 6 was moved to provide a better sightline through the corner. Turn 7 was sharpened to slow down racers prior to entering the back straight. Formula One-style curbs were also installed on the track. The track reopened on February 23, 2008, with a ribbon cutting ceremony.