Washington State Route 900

On Sunday, June 29, 2025, we drove Washington State Route 900, heading east on the old highway.

State route No. 900:

A state highway to be known as state route number 900 is established as follows:

Beginning at a junction with state route number 5 in Seattle near the Duwamish River, thence southerly by way of Renton to a junction with state route number 90 in the vicinity of Issaquah.

Highway 900 begins here at the north end of Tukwila, at an interchange with I-5. Once upon a time, it began in downtown Seattle but that part was removed in the great clean-up of 1991.


A half mile later, here's the other half of the interchange with I-5.


Highway 900 thence steadily climbs the hill, four lanes of concrete surrounded by forest. Cambell Hill, Earlington. Try to go the speed limit, I dare you. We drop back down into Renton. Signage for 900 disappears. We have arrived at the junction with SR 167. 900 used to go straight ahead, but Renton petitioned the state for the city to take over those streets, which they did in 2018. You'd think there is a gap in 900 now, but the code description above doesn't have a gap. For many years, there's been a concurrency with 405 on the east side of town. Now there must be an even longer concurrency. We turn right to join 167 southward.


After many stoplights on Rainier, we arrive at Highway 900's interchange with SR 167 and I-405. We shall go north on 405.


Shortly after merging onto I-405, there's a junction with SR 515. Since it's just an onramp, I forgot to have Isabelle photograph it. Here's a photo from the same spot ten years ago.


Around the corner, we reach the interchange with SR 169. Still on I-405, too, of course. This used to be signed for 900 west into Renton, but 900 and 405 were actually parallel right here (until 2018).


We then pass the onramp where 900 once joined I-405, before 2018. Even earlier, it just crossed 405 at that point, but then it was moved to the larger Sunset Blvd, connecting at the next interchange, which is photographed above. We'll now leave 405.


Highway 900 climbs to the Renton Highlands on Sunset Blvd (once part of the Sunset Highway, naturally). It's five lanes of broad, sweeping curves through shopping centers and old suburbia. Then we abruptly cross a line on the map and it's a two-lane rural road with tight turns. Up and down to May Valley, then bigger up and down through canyons of the Issaquah Alps. 900 spits out into a speedway into western Issaquah, all the way to I-90. Highway 900 thus ends.

Once upon a time, this highway was one of the main routes from Seattle to Snoqualmie Pass, so the highway actually turned east a bit before its current end, went through the heart of Issaquah, and climbed to the mountains and beyond. No more, though. Now it's broken bits of history. Old concrete, city streets, a concurrency surely ignored by everyone but me, and a hint of the Sunset Highway.