The Tacoma Narrows Bridge collapsed because of winds on November 7 that year, earning it the name Galloping Gertie.

[9] A combined state department of transportation was proposed in the mid-1960s and gained the support of Governor Dan Evans.

William A. Bulley, the existing Director of Highways, was appointed as the state's first Secretary of Transportation to lead the new agency, which had absorbed state departments that had overseen highways, toll bridges, aeronautics, canals, and community development.

In 1980, Mount St. Helens erupted and caused damage to many state highways, mainly SR 504.

The 2001 Nisqually earthquake damaged most state highways around the Seattle metropolitan area and most of the budget was turned over to the Puget Sound region to help rebuild and repair roads and bridges.

[15][16] Since the beginning of the 21st century, WSDOT has been tasked with rebuilding and renovating aging portions of the highway system across the state.

Several sections with poor conditions required emergency repairs in early 2023, including a large hole in an offramp to SR 99 in Seattle and broken concrete panels on I-5 in Everett and I-90 near Issaquah.

[17] WSDOT has also been tasked with replacement of 437 fish barriers, mainly outdated culvert designs, in Western Washington to comply with a federal court order to restore salmon runs that are protected by Native American treaty rights.

The last Secretary of Transportation was Lynn Peterson, who served until February 5, 2016, when her appointment under Governor Jay Inslee was rejected by the Washington State Senate during the confirmation process.

[29][30] WSDOT has approximately 1,500 positions for winter operations, which includes snow plow crews for the major mountain passes crossed by state highways.

[31] In the Snoqualmie Pass area, the agency has avalanche control crews that use an M60 tank, howitzers, and a mechanical tram carrying explosives to clear snow buildup before it endangers the highway.