How I-90 stitches together a cross-country route
Interstate 90 runs from Seattle to Boston, linking the Pacific Northwest with New England. Its roughly 3,000-mile length can make it sound like one continuous piece of engineering, but it is better understood as a chain of highway segments, each built and maintained to serve the conditions of the region it crosses.
The route passes through varied terrain, from the mountains and broad plains of the West to the more densely settled Northeast. That variety shapes the drive: grades, weather, traffic, and the spacing of towns and services all change along the way. Drivers may stay on the same numbered interstate, but the road around them is never quite the same.
A number that helps organize the journey
I-90’s even number marks it as an east–west route in the U.S. Interstate system. That numbering convention gives drivers and planners a broad sense of direction, while interchanges connect the long-distance route to cities, local roads, and other interstates. The result is not simply a line between two coasts, but a corridor that carries regional trips as well as cross-country traffic.
That is the practical achievement of a coast-to-coast highway: it makes a journey across very different landscapes possible without requiring travelers to piece together a new route at every state line.
