History, archaeology and culture

We strive to highlight historically significant features of Washington that demonstrate creative mitigation efforts and preserve and present the history of our transportation system.

Find videos, project webpages, information centers, and publications that demonstrate the results of creative mitigation and notable historical resources describing the history of Washington’s Transportation system, including


  • Ebey Slough Bridge (SR 529)
    • Remembering the Ebey Slough Swing Bridge – This video describes how the Ebey Slough Bridge served Snohomish County for 85 years before being replaced in 2012. Of the 16 swing bridges in 1944, only three remain today.
  • Lacey V. Murrow Memorial Bridge (I-90 Floating Bridge)
  • Manette Bridge (SR 303)
    • The Manette Bridge: Bringing People Together for 81 Years – In the 1920s, it was apparent that the communities of Manette and Bremerton needed a bridge to connect them. High costs prevented financial backing from being offered on a city, state, or federal level. Learn about how the bridge came to be built through the collaborative efforts of the city and Navy.   
  • Puyallup River/Meridian Street Bridge (SR 167)
    • The Historic Meridian Street Bridge - For more than eight decades, the Meridian Street Bridge over the Puyallup River has served as a portal for cities along the Puget Sound to the community of Puyallup. Significant for its unusual truss configuration using an unusual parabolic top cord truss design, it is the only one of its kind in Washington.
    • SR 167 Puyallup River Bridge Move – Watch a time-lapse video of the historic 1920s era steel bridge as it is lifted and moved about 60 feet to the east.
  • Simpson Avenue Bridge (US 101)
  • Tacoma Narrows Bridge
    • SR 16 Tacoma Narrows Bridge Project – The website provides information on the design, engineering, and people responsible for the fateful 1940s bridge known as “Galloping Gertie,” the 1950s replacement, and the addition in 2007 of the parallel eastbound bridge. The site includes lesson plans developed for grades 1-4 in Social Studies, Math, Science, and Language Arts for educators.
  • Historic highway bridges



Ethnobotany is the study of the relationship between cultures and plants. As part of our aim to avoid adverse effects to historical, archaeological, and cultural resources, WSDOT promotes the protection and preservation of ethnobotanical resources.

The WSDOT Manual on Ethnobotany and Cultural Resources  is a condensed list of western Washington plants compiled by Scott Clay-Poole, PhD. The manual covers

  • Herbs
  • Shrubs/trees
  • Conifers
  • Ferns & fern-allies
  • Lichens



  • Interstate 5 (I-5)
    • The Weedin Place Nuclear Fallout Shelter was built as a prototype in 1963 to be the model for countless similar shelters that would be installed nationwide under interstate highways. The fallout shelter supports the southbound lanes of I-5 and is considered a feature of the federal interstate highway system. Learn more in the publications below:
  • SR 520
    • 520history.org – Learn about 13,000 years of the landscapes, communities, and industries along the SR 520 corridor across Lake Washington. This documentation was developed as mitigation for the SR 520 Bridge replacement and HOV Project.
  • SR 99: Alaskan Way Viaduct Replacement


Historic highways

Washington State has several historical highways that are representative of early twentieth century highway engineering and design. These highways maintain the original alignment, road prism, and site distance providing the experience of traveling on a truly historic roadway.

Federal and state laws and regulations mandate that the transportation project development process take into consideration cultural resources that may be affected by project activities. This includes impacts to bridges and roadways at least 50 years old and deemed significant according to the National Register of Historic Places (NRHP) criterion for listing. The Washington State Department of Transportation (WSDOT) maintains an inventory of historic bridges and highways that have been evaluated for the NRHP.

You can find interpretive historical highway markers along state highways and scenic byways throughout Washington. Use the map and list below to find marker locations. Click on each marker’s picture to enlarge.