The Petit Jean River is a river in west-central Arkansas. The river rises in the Ouachita Mountains in northern Scott County; it flows through Logan County and Yell County, defining the border between Yell County and Conway County before reaching its mouth at the Arkansas River north of Petit Jean State Park. The city of Danville, named after a steamboat that navigated the river in 1840, is the largest settlement on the river. Blue Mountain Lake, which straddles the border between Logan and Yell Counties, was created when the river was dammed in 1947. The river is the longest located entirely within the Arkansas River Valley.