Did you know that one of Washington's first cross-state highways, the Sunset Highway, provided the first automobile route over the Cascade Mountains? When it opened in 1915, the highway largely followed the route of an Indian trail that had been developed into a wagon road. The Sunset Highway changed designations a number of times over the years.... being known as Highway #2, U.S. 10 and Interstate 90. The route serves as the primary east-west route in Washington." So states the HistoryLink article by Jennifer Ott.
As early as 1853, a passable route over Snoqualmie Pass was becoming a necessity. There were several trails connecting points in Washington, but the Cascades were a major headache to cross. By 1867, a wagon road was open from North Bend to Easton. A 1906 report emphasized the importance of such a route, calling it "the most important trans-mountain road projected."
The 1909 Alaska-Yukon-Pacific Exposition's transcontinental auto race form New York to Seattle underscored the urgent need for better roads. During the race, cars were frequently bogged down in mud, particularly along some sections over Snoqualmie.
By 1913, the Sunset Highway was designated as a primary state route and on July 1, 1915, it was officially opened. But what did it look like then compared to today??
I've been state-crossing in I-90 since 1954 and I can tell you that without a doubt there has not been a single year without road construction! The route is getting busier and busier and better and better all the time.
And by-the-by, it's Sno-qual-mie NOT NOT Sno-qual-a-mie.