Phoenix International Raceway, or just PIR, is a one mile tri-oval race track located in Avondale, Arizona. It opened in 1964, as the new home of major open-wheel racing in the Phoenix area, replacing the track at the Arizona State Fairgrounds as an automobile racing venue. Unfortunately, due to a change in focus by the track's current owners, ISC, the Phoenix area's long history of hosting Indy-style racing (only Indianapolis itself and Milwaukee have had more) came to an abrupt end in 2005, when PIR failed to host an Indy Racing League event for the first time. Ironically, stock car racing's top series, NASCAR's Nextel Cup, didn't even run at PIR until 1988. Their inagural race was won by the late Alan Kulwicki, who debuted his Polish Victory Lap here after taking the checkered flag.

PIR has a unique tri-oval shape, with a curve in middle of its backstreatch between turns two and three, commonly referred to as "the dogleg". This exists because the original builders were constrained by both the rocky hills located on the property and their incorporation of an extenal road course and dragstrip into PIR's design. Once nearby Firebird International Raceway became a regular stop on drag racing tours, PIR's dragstrip was rarely used. The external road course, which was used mainly for private testing and as parking lot access roads during oval events, was later replaced by the current infield road circuit. Prior to construction of a tunnel under turn four in 2004-05, the only access to the PIR's infield during events was via crossovers, where the old external road course and dragstrip intersected the oval. Once the tunnel was built, the crossovers were permanently sealed off.

The other notable feature of PIR is the presence of the the "Hillside", a fan-favorite viewing area located on Monument Hill just outside of turn four. At the top of this hill lies a USGS bench marker. Long before PIR existed, this spot was the original land survey point for all of what later became the state of Arizona. The original surveyors chose this location to begin their work because it is the nearest high ground from the confluence of the Salt River and the Gila River, and offered a great view after only a gentle climb. The present-day Avondale Boulevard (formerly known as 115th Avenue) marks the north-south meridian of that original survey, while the aptly-named Baseline Road runs east-west along the surveyors' baseline. The survey benchmark also denotes the western boundary of the Gila River Indian Community. In PIR's earlier years, residents of this neighboring Native American community were rumored to have sometimes sold concessions through the fence to hungry race fans unwilling to walk back down to the track's food and beverage stands.

Until 2005, PIR's oval annually hosted at least one major Indy-style racing event, dating back to its initial construction. It is still used year-round by various Indy Racing League teams for private testing as well as for the filming of television commercials featuring that series' cars.

The infield road course, originally built for IMSA was most recently used by the Grand American Road Racing Association.

The oval also remains home to what was traditional called the Copper World Classic, a weekend of predominently open-wheel comptition with USAC midget and Silver Crown cars as well as modifieds. From 2002-04, the event was incorporated into early-spring the Indy Car Series / Indy Pro Series weekend, but with the departure of IRL, the Copper World event has returned to its original late-winter date on PIR's racing schedule.

In 2005, the track hosted a second NASCAR Nextel Cup race event, replacing the spring race formerly held at Darlington Raceway, in South Carolina.