On October 18, 1928, a new highway connecting Seattle and Tacoma opens. The 24-mile road runs southeast out of Seattle along East Marginal Way and across the new Duwamish River Bridge, then travels south through Riverton and past Angle Lake before turning west at Milton and proceeding to Tacoma. The new highway is a marked improvement over the two existing roads commonly used in the 1920s to travel between the two cities. It becomes part of the Pacific Highway, later U.S. Route 99, which runs from Vancouver, British Columbia to San Diego, California, and will serve as the main West Coast transportation artery before it is surpassed by Interstate 5 in the 1960s.
In the earliest years of the twentieth century a network of local roads, mostly unpaved, connected Seattle and Tacoma. Interurban service between the two cities, which began in 1902, was the best way to get between them; the trip took either an hour and 40 minutes (with multiple stops) or an hour and 10 minutes on the limited. This worked well for a time, until the automobile began to make both the horse and the interurban obsolete.
An early segment of the Pacific Highway, usually referred to locally as the West Valley Road, was completed between Seattle and Tacoma by late 1915. However, taking it wasn't any faster than taking the limited. By the mid-1920s, the explosive growth of the automobile was mandating the construction of better roads. A new highway between Seattle and Tacoma had been under consideration for several years, and after some talk of placing it slightly farther east, the final route was chosen by the state highway department in 1924. Grading for the new road began later that year and was completed by the spring of 1927.
The 1927 Legislature appropriated funds to pave a 20-foot-wide concrete lane from Seattle to the newly completed Puyallup River Bridge (now  the Puyallup Avenue Bridge) at the edge of Tacoma, and the appropriation included funding for a new bridge for the highway across the Duwamish River just west of the extant bridge on East Marginal Way. (The legislature also increased the state highway speed limit from 30 to 40 miles per hour, which generated as much excitement as the announcement of the new highway.) A second 20-foot-wide lane was planned to be built next to the first after it was completed, and the entire project was priced at $3,065,000 ($46 million in 2021 dollars).
The West Valley Road and the High Line
In 1927, the southbound West Valley Road followed a 33.4-mile route out of Seattle along East Marginal Way to today's Interurban Boulevard, then through Tukwila and south on the West Valley Road to Sumner before pivoting west to Tacoma. Though this was considered the primary roadway between the two cities, a second route had gained a substantial following by the early 1920s, so much so that for a time there was talk of making it the main route. Known as the High Line, this way was much shorter at 24 miles. But it was a more difficult journey, with more hills and curves than the West Valley Road. Further, only part of the High Line was paved, and some of that pavement was bricks.
In 1927, the southbound High Line left Seattle and crossed the Duwamish River on the 14th Avenue Bridge at South Park before connecting with what is now known as the Des Moines Memorial Drive. During the early 1920s, 1,432 American elm trees were planted along the nearly 10-mile drive from the Seattle city limits to the Kent-Des Moines Highway as a living memorial to the state's World War I dead, and this stretch of roadway was later renamed accordingly. The memorial drive ended in Des Moines, and from there the final 13 miles to Tacoma was gravel. The road followed today's Marine View Drive S through Redondo and edged west on Dash Point Road before turning south again for a dramatic ending on the approach to Tacoma. Here the High Line dropped down the big hill at Julia's Gulch, a dangerous, winding traverse, but with striking views of the Tacoma Flats below.
New and Improved
Grading had first been completed on the southern end of the new highway and the work had had more time to settle, so this part of the road, between Redondo and Tacoma, was paved first. The work was largely completed by November 1927, and the southern section of the highway opened to traffic in December. Work on the northern section was completed in October 1928, and the highway was dedicated by an entourage of Seattle and Tacoma officials on the afternoon of October 18. They first met at the northern intersection of the highway and the West Valley Road, a mile or so south of Boeing Field, to cut the ceremonial ribbon formally opening the new route, then caravanned to Angle Lake for dedicatory speeches.
The highway helped hasten the end of the interurban between Seattle and Tacoma, which shut down at the end of 1928. Its adjacent concrete lane opened to traffic in the early 1930s, making it a four-lane highway and making it easier for motorists to enjoy that new 40-mile-per-hour speed limit.