Secondary State Highway 2D

SSH 2D was added to the state highway system in 1937. This route began at Jct PSH 2 (at the time also US 10, now SR 900) on the west side of Issaquah and headed northerly along West Lake Sammamish Parkway to Redmond, then westerly, ending at Jct SSH 2A in Downtown Kirkland. A spur of SSH 2D crossed the Sammamish River at Redmond and connected the SSH 2D trunk with PSH 2 (Bothell Branch) in Downtown Redmond.

In 1957, when the PSH 1 designation replaced the SSH 2A designation, SSH 2D was shortened on the Kirkland end. Instead of ending in Downtown Kirkland, the interchange of PSH 1 and SSH 2D east of Downtown Kirkland became the NW terminus of SSH 2D. In 1959, the PSH 1 to Downtown Kirkland portion of SSH 2D was added back to the state highway system. The state ended up building a new bridge over the railroad tracks between PSH 1 (I-405) and Downtown Kirkland in the 1960s. SSH 2D had originally passed beneath these tracks via an underpass with low clearance.

In 1963, SSH 2D was extended south from Downtown Kirkland to a junction with the Evergreen Point Branch of PSH 1 (now SR 520). When the current state highway numbering system was first posted in January 1964, SSH 2D became SR 901.