When the current state highway numbering system was first posted in January 1964, SR 294 started at Jct US 395 in Colville and headed ENE via Tiger Pass to Jct SR 31 at Tiger, where SR 294 ended. In 1973, after completion of the North Cascades Highway in September 1972, SR 20 was extended from its original eastern terminus in the Omak-Okanogan area to Newport. SR 294 was redesignated SR 20 as part of this extension.
Before 1964, SR 294 had been SSH 6A.
Primary State Hwys Secondary State Hwys