Seattle is 175 miles north of Portland along I-5, about 2.75 hours without traffic. Exit central Portland on I-405 north, which crosses the Willamette River over the arch of the Fremont Bridge. Join I-5 north, which runs through residential Portland before crossing the wide Columbia River and entering Washington.
After traversing the city of Vancouver, Washington (not to be confused with Vancouver, British Columbia), I-5 runs north through rural farmland and along the Columbia River, past the small cities of Kelso, Longview, Chehalis, and Centralia.
The state capitol dome is visible from the freeway as I-5 turns northeast in Olympia; the scenic view of the Nisqually National Wildlife Refuge marks your last stretch of uninterrupted greenery.
Traffic can get thick through the Joint Base Lewis-McChord and the industrial city of Tacoma, 32 miles south of Seattle. As you follow I-5 north into downtown Seattle, the freeway narrows and passes through several short tunnels.
Excerpted from the First Edition of Moon Pacific Northwest Road Trip.