It’s been the main north-south freeway on the West Coast for decades, and the go-to route for motorists traveling between Seattle and Portland. But many generations of Washingtonians have no idea what life was like before or during the time Interstate 5 was built.

The second contender for this month’s “Archives treasure” gives you a glimpse at I-5’s construction through Seattle in the late 1950s and early ‘60s. It’s a collection of photos from the state Department of Transportation showing the freeway being built. The photo above looks north toward Wallingford and the University District. The photo below features freeway work in downtown Seattle.

The first Archives treasure this month is a 42-star U.S. flag from 1889. The third treasure will be featured early next week.