State Route 261 (SR 261) is a 62.71-mile-long (100.92 km) state highway in the U.S. state of Washington. Serving Columbia, Franklin, and Adams counties, the highway begins at U.S. Route 12 (US 12) east of Starbuck and becomes concurrent with SR 260 from Kahlotus to SR 26 in Washtucna before ending at Interstate 90 (I-90) and US 395 in Ritzville.