SR 432 begins at an intersection with the Ocean Beach Highway, signed as SR 4, in West Longview in Cowlitz County. The two-lane highway travels southeast as Willow Grove Connection Road and Industrial Way around Mount Solo and into the city of Longview. The four-lane SR 432 parallel to a Columbia and Cowlitz Railway line and the Columbia River through the Port of Longview and intersects the northern terminus of SR 433, which travels on Oregon Way and the Lewis and Clark Bridge to Rainier, Oregon. The highway turns northeast onto 3rd Avenue and crosses a BNSF rail line before it intersects the Tennant Way divided highway and the southern terminus of SR 411 in a partial cloverleaf interchange.^[3] The SR 432 designation travels onto four-lane Tennant Way grade-separated highway and continues southeast, parallel to a BNSF rail yard, before intersecting Dike Road in a partial cloverleaf interchange and crossing over the Cowlitz River into Kelso.^[4] The highway travels south of Southwest Washington Regional Airport and intersects Talley Way in a partial cloverleaf interchange before intersecting I-5.^[5] The partial cloverleaf interchange, nicknamed the Longview Wye,^[6] serves as the eastern terminus of SR 432 while the roadway continues south as the Old Pacific Highway.^[7][8][9]

Every year, the Washington State Department of Transportation (WSDOT) conducts a series of surveys on its highways in the state to measure traffic volume. This is expressed in terms of annual average daily traffic (AADT), which is a measure of traffic volume for any average day of the year. In 2011, WSDOT calculated that the busiest section of SR 432 is the bridge over the Cowlitz River, serving 30,000 vehicles, while the least busy section is the western terminus at SR 4 in West Longview, serving 3,500 vehicles.^[10] The entire route of SR 432 is designated as an Intermodal Connector within the National Highway System,^[11] a highway system that includes roadways important to the national economy, defense, and mobility;^[12] and as a Highway of Statewide Significance by WSDOT,^[13] which includes highways that connect major communities in the state of Washington.^[14] SR 432 forms part of the Seattle to Portland Bicycle Classic, serving as the link between Longview and the Lewis and Clark Bridge via 3rd Avenue on the 202-mile-long (325 km) bicycle race held annually.^[15][16]

SR 432 has been part of the Washington state highway system since 1937, when it was designated as a branch of PSH 12.^[17] The Longview–Kelso branch of PSH 12 traveled 5.47 miles (8.80 km) east from an intersection with the Ocean Beach Highway, signed as PSH 12 and U.S. Route 830 (US 830), onto Nichols Boulevard around Lake Sacajawea and Tennant Way in Longview and crossed the Cowlitz River to Kelso, where the highway ended at an intersection with the Pacific Highway, signed as PSH 1 and US 99.^[18][19][20] In 1952, the highway was proposed as U.S. Route 830 Alternate shortly after the completion of the Longview Wye on US 99 (now I-5).^[21]

The Longview–Kelso branch of PSH 12 was replaced by SR 832 during the 1964 highway renumbering and existed until US 830 was decommissioned in 1967,^[22] as SR 432 was established as an auxiliary route of SR 4 before the highway system was codified in 1970.^[2][23][24] SR 432 was re-aligned onto its present route, Industrial Way,^[25] in 1991 to end at SR 4 in West Longview and to serve the Port of Longview.^[2][26][27] The realignment took effect on April 1, 1992.^[28] The eastern terminus of SR 432, an interchange with I-5 nicknamed the Longview Wye,^[6] was reconstructed by WSDOT beginning in December 2009.^[29][30] WSDOT removed the northwest loop ramp, which connected Old Pacific Highway to southbound I-5,^[31] and replaced it with an improved interchange with Talley Way that opened on October 28, 2011.^[5][9][32]

The entire highway is in Cowlitz County.

• Highways of Washington State