SR-18 — Downtown to Berrydale

The corridor began as branches of earlier state highways, created in 1931 and 1949. The Echo Lake Cutoff was built as a two-lane road, routed to avoid Tiger Mountain on the way from Tacoma toward Snoqualmie Pass. Its first section, between US 99 and Auburn, opened on December 19, 1958, and the final 7 miles, from the entrance to Tiger Mountain State Forest to Interstate 90, opened on December 1, 1964. The SR 18 number came with the 1964 state highway renumbering. In 1992, after a decade of accidents had given it a reputation as a dangerous roadway, work began in Auburn to widen it into a four-lane freeway, reaching Federal Way in 2007. Berrydale, an unincorporated community, had a post office established in 1921. [1]