The track began as a five-eighths-mile (one km) clay oval in 1924 on the site of a field in north Portland.

[2] Mike Skinner and Ron Hornaday Jr. won at Portland during their championship seasons, 1995 and 1996 respectively.

[2] Other notable winners included future NASCAR Winston Cup champion Bobby Allison, 1990 Daytona 500 winner Derrike Cope, and NASCAR drivers Chad Little, Greg Biffle, and Ken Schrader.

[3] The track held a total of seven NASCAR Cup Series races during the 1956 and 1957 seasons.

[1] The track was converted to a clay surface and hosted the World of Outlaws Sprint Cars in 2000 and 2001.