Primary State Highway 1-Pacific Highway

PSH 1 (Trunk)

PSH 1 started at the Interstate Bridge across the Columbia River between Portland, OR and Vancouver, WA. From Vancouver, PSH 1 headed north via Kelso, Centralia, Olympia, Tacoma, Seattle, Everett, Mount Vernon, and Bellingham to Blaine. At Blaine, PSH 1 ended at the US-Canadian border. In late 1926, PSH 1 was also designated as US 99. As newer sections of US 99 and later I-5 were built, the PSH 1 designation was moved to the newer alignment. Today, PSH 1 is I-5.

PSH 1 TR (Truck Route)

PSH TR connected with PSH 1 in the south end of Blaine and went north to truck customs at the US-Canadian border. Today, PSH 1 TR is SR 543.

PSH 1 AP (Austin Pass Branch aka Mt. Baker Highway)

PSH 1 AP began in Bellingham at Jct PSH 1 and headed east to Mt. Baker and Austin Pass. When the Bellingham Freeway (PSH 1 or I-5) opened in 1962, the downtown to freeway portion of PSH 1 AP was dropped from the state highway system. Today, PSH 1 AP is SR 542.

PSH 1 CD (Chuckanut Drive Branch)

PSH 1 originally followed Chuckanut Drive between Burlington and Bellingham. This route was signed as US 99 after 1926. In the mid 1930s, a newer PSH 1 alignment was built from Burlington via Alger and Lake Samish to Bellingham. US 99 was shifted to this newer alignment. The Chuckanut Drive route was redesignated PSH 1 CD and signed for a time as Alt US 99. Today, PSH 1 CD is SR 11.

PSH 1 AN (Anacortes Branch)

PSH 1 AN linked Mount Vernon with Anacortes. When the current state highway numbering system was first posted in 1964, PSH 1 AN was signed as SR 536. The North Cascades Highway was completed in September 1972. The SR 20 designation was then extended west from its original western terminus at Jct SR 536 at Fredonia, approx five miles west of Mount Vernon and Burlington. The SR 20 designation replaced SR 536 from Fredonia to Sharps Corner. At Sharps Corner, SR 20 turned left and headed south via what had been SR 525. SR 20 Spur continued along former SR 536 and PSH 1 AN to the state ferry terminal in Anacortes.

PSH 1 MA (Marysville Branch)

PSH 1 MA started at Jct PSH 1 in Marysville and headed east to Jct SSH 1A near Lake Stevens. At least, it did so on paper. A missing gap in the middle of the route was not completed until the 1980s, long after the PSH numbering system had been replaced. Today, PSH 1 MA is SR 528.

PSH 1 RE (Renton Branch or Renton Freeway)

PSH 1 RE was designated as such in 1957 after the I-405 general corridor was approved. PSH 1 RE started at Jct PSH 1 at Riverton Heights near Tukwila, headed east to Renton, then curved north to Bellevue and Bothell, then NW to Jct PSH 1 in Alderwood Manor. Before being designated as PSH 1, the Riverton Heights to Renton highway had been SSH 1L and the Renton to Bothell highway SSH 2A. There was no direct state highway from Bothell to Alderwood Manor until I-405 was built there in the late 1960s. Since there was no Interstate Highway numbering system when funding for the Interstate System was approved by congress in 1956, PSH 1 RE was to have been signed as US 99E. The Interstate numbering system was devised later in 1957 and PSH 1 RE was designated at that time but not posted then as I-405. When the present state highway numbering system was first posted in 1964, freeway portions of PSH 1 RE were posted as I-405 and non freeway portions as SR 405. By around 1970, the last SR 405 signs were replaced by I-405 signs. When I-5 was opened thru Tukwila in 1967 and I-405 connections completed near Southcenter, the southern terminus of PSH 1 RE may have been shifted eastward from former Jct PSH 1 (now SR 99) at Riverton Heights to Jct PSH 1 (I-5) at Southcenter in Tukwila. All of PSH 1 RE is now I-405.

PSH 1 WM (West Marginal Branch)

PSH 1 WM was built as a freeway in stages durring the 1960s. The First Ave S Bridge to 14th Ave S/Des Moines Way portion was built first, Des Moines Way to Pacific Hwy later. Until the route continued thru, it was signed as Temp US 99. PSH 1 WM was completed about the time that US 99 was decertified as a US highway. The SR 99 designation was switched from East Marginal Way to PSH 1 WM. The West Marginal Freeway was extended SE from Jct SR 99 at Pacific Hwy S to Jct I-5 Exit 156.

PSH 1 EP (Evergreen Point Branch)

PSH 1 EP ,including the Evergreen Point Floating Bridge, opened to traffic from I-5 Exit 168B to Lake Washington Blvd/104th Ave NE (now Bellevue Way) in August 1963. Northup Way was used as the temporary route of PSH 1 EP the rest of the way to PSH 1 RE (I-405). The State Highway 1 signs were only posted on this portion of PSH 1 RE for a few months. In January 1964, the route was resigned as SR 520. PSH 1 RE was planned to extend to Jct PSH 2 BO in Redmond. This route was built on stages, partly after the PSH 1 EP designation was dropped. Today all of PSH 1 EP is SR 520.

PSH 1 (branch-no letter designation-East Vancouver Bypass)

PSH 1 East Vancouver Bypass did not open until after the PSH numbering system was done away with. This route opened in stages between the mid 1970s and December 1982 and is I-205.

PSH 1 DC (Duwamish Connection?-Boeing Access Rd)

PSH 1 DC was built in the early 1950s south of Boeing Field to link PSH 1 with PSH 2 RE. PSH 1 DC included an interchange with Airport Way and a bridge over the NP-UP-PC-CMStP&P railroad mainlines. Signed as part of SR 181 in 1964, PSH 1 DC was dropped from the state highway system in the later 1960s or 1970s.