The road between Oregon's Willamette Valley, where Portland sits, and the Pacific coast is known for recreation, wineries and beauty.
This weekend, it will also be known for slow traffic, the group said in a study titled "Are We There Yet?"
Interstate 64 in the Tidewater region of southeastern Virginia is second on the group's list of vacation bottlenecks, followed by the Maryland-Delaware shore, Branson, Missouri, and North Carolina's Outer Banks.
Rounding out the Top 10 are Cape Cod, the Jersey Shore, California's Napa Valley, the Amish country of Pennsylvania and the Catskill Mountains in New York.
"Part of slowing down is about relaxing," said Greg Cohen, president of the group. "But slowing down because you're stuck in traffic is very frustrating."
An estimated 33.9 million people are expected to travel by motor vehicle during the holiday weekend, according to AAA.
Whew I hope we don't run into too many of them going to Baltimore :P