The Portland International Raceway was constructed on the site of the old settlement of Vanport (Oregan) that was swept away in 1948 by a flood. The circuit itself is found in Delta Park, an industrial and research complex at the confluence of the Willamette and Columbia rivers. The first motor races were held in 1961, beginning a tradition that continues to the present day.

In its current layout, the circuit measures 1.944 miles. It has twelve curves and the main straight (also used for drag racing) is interrupted by a series of chicanes named 'festival turns'. A short straight leads into the slower part of the circuit (curves 4, 5, 6 and 7). Finding the right racing line is crucial here in setting a good lap time. Getting the braking right for the first right hander is fundamental as it is important to be in a position in order to maintain a high tempo throughout the rest of the section. After turn 7 the circuit evens out. A fast 'esse' comes up next and this leads into a quick right hand curve. The section immediately before the main straight is composed of a tricky left-right and a sharp right hander.

The American Le Mans Series was held at Portland in 1999, 2000, 2001 and 2004.