Secondary State Highway 3A

SSH 3A was added to the state highway system in 1937. This route began at Jct PSH 3 (US 97/US 410) at Union Gap and headed southeasterly, crossing PSH 8 (US 97) at Toppenish, and ending at Jct PSH 3 (US 410) in Prosser. In the early 1960s SSH 3A from Union Gap to Toppenish was signed as Alt US 97. Since January 1964, SSH 3A from Union Gap to Toppenish has been part of US 97 and from Toppenish to Prosser part of SR 22.