Primary State Highway 6 (PSH 6) was a Washington state highway in the older primary and secondary system that existed from 1937 until 1964 in Spokane and Pend Oreille counties. The road ran from an intersection with PSH 3, U.S. Route 2 (US 2, formerly US 195 and US 10 Alternate) and US 395 in Spokane north to British Columbia Highway 6 (BC 6) at the Canada–US border near Metaline Falls, passing its branch route and two secondary routes.