Secondary State Highway 11B

SSH 11B was added to the state highway system in 1937. This route originally began at Jct PSH 11 (US 395) in Connell and headed east via Kahlotus, Washtucna, and La Crosse, and ended at Jct PSH 3 (US 295) at Dusty.

In 1957, the route description in state law was reversed. Also, that portion of SSH 11A heading west from Connell to Jct SSH 11G (now SR 17) was transferred to SSH 11B.

A branch was added to SSH 11B in 1957 extending southerly towards Lyons Ferry, then southeasterly via Starbuck, ending at Jct PSH 3 (at the time US 410, now US 12). There were provisions in the law that the state not take over the existing county roads immediately. The state intended to build a new road directly south from Washtucna to the Snake River. Also, the existing route crossed the Snake via a ferry.

The I-90 bridge across the Columbia River at Vantage replaced an older 2 lane bridge built around 1926 or 27. The old Vantage bridge was disassembled, trucked to the Lyons Ferry area, and reassembled across the Snake River. This bridge, including new approach spans, opened to traffic in 1968 or 69. The Highway Commission adopted the McAdam to Delaney route of SSH 11B as a state highway in February 1969. The shortcut from Washtucna to the Snake River was never built.

When the current state highway numbering system was first posted in January 1964, the east-west section of SSH 11B from Jct SSH 11G (SR 17) west of Connell to Washtucna became signed as SR 260. The Washtucna to Dusty section of SSH 11B became part of SR 26. After the old Vantage bridge was relocated to Lyons Ferry, the SSH 11B branch from McAdam to Delaney became part of SR 261.