WSDOT (former) Milepost 31 exterior
Milepost 31 closed on November 25, 2017. Its exhibits have been preserved in a virtual library: http://www.milepost31.com.
Milepost 31 was an award-winning information center in Seattle’s Pioneer Square neighborhood. Between 2011 and 2017 it welcomed almost 80,000 visitors from nearly 80 countries to the neighborhood and the SR 99 Tunnel Project. The center got its name because of its proximity to milepost 31 on SR 99 as the highway winds through downtown Seattle. Milepost 31 was located at 211 1st Ave S in Pioneer Square.
The center highlighted the people and projects that shaped the land that became Pioneer Square, and provided an inside look at the SR 99 Tunnel Project. Milepost 31 featured history, artifacts and exhibits designed to broaden visitors’ understanding of the land beneath them. Tour guides also led approximately 1,730 free tours explaining the effort to replace the Alaskan Way Viaduct. The tours included a climb to a closed section of the viaduct, where members of the public could gaze down upon the tunnel’s ever-changing south portal construction site.
Big Bertha tunneling machine model WSDOT photo
Why the name “Milepost 31”?
Mileposts mark progress. They help you track where you are on your journey, reminding you of the places you’ve passed through on your way to somewhere else.
But what if a milepost is so interesting that it becomes a destination? Located on SR 99 at the western edge of Pioneer Square, Milepost 31 is that kind of place.
It marks a spot on the highway, but it also marks the spot where, before mileposts existed, mile-thick glaciers gave way to native civilizations. It’s where Seattle’s first neighborhood saw the rise of the city’s most notorious stretch of highway – the SR 99 Alaskan Way Viaduct – and where crews building the world’s largest diameter bored tunnel to replace the viaduct will first cross into the soils beneath Pioneer Square.
SR99 tunnel WSDOT project after Bertha
