State Route 10 (SR 10) is a state highway in the U.S. state of Washington. The highway is a remnant of U.S. Route 10 (US 10) in Kittitas County, traveling southeast along the Yakima River from SR 970 in Teanaway to US 97 northwest of Ellensburg. SR 10 was established in 1970 as the successor to US 10 after the completion of I-90 across the Snoqualmie Pass in 1968. The highway was previously part of State Road 3 from 1923 to 1937 and Primary State Highway 3 (PSH 3) until the 1964 highway renumbering.