At different times, two different routes have been designated SR 143.
Earlier SR 143
When the current state highway numbering system was first posted in January 1964, SR 143 ran from Jct SR 14 (now US 12) a few miles NE of Packwood north into Mount Rainier National Park and ended at Jct US (now SR) 410 at Cayuse Pass. In later 1967, this earlier SR 143 was redesignated SR 123 at the time US 12 was extended into Washington State. The SR 143 designation went into disuse.
Before 1964, this earlier SR 143 had been the Cayuse Pass branch of PSH 5.
Later SR 143
A second SR 143 was added to the state highway system in 1973. This newer SR 143 connected SR 14 at Plymouth with the Umatilla Bridge across the Columbia River between Plymouth, WA and Umatilla, OR. This bridge, a steel thru truss cantilever built in the mid 1950s, had originally been owned by Umatilla County and operated as a toll bridge. The precise route of I-82 was determined later than the routes of I-5 and I-90. In the mid 1970s, the Plymouth-Umatilla crossing had finally been designated as part of the I-82 corridor. The bridge came under state ownership and the tolls were removed. The SR 143 designation was used temporarily for about a decade until 1985 when I-82 was opened to traffic from the south end of the Tri-Cities to the Columbia River.
Primary State Hwys Secondary State Hwys