This drive is known as the "Cascades Loop" and is pretty popular with motorcyclists. The Destination Highways book rates the road across the North Cascades as the Number One road in Washington. Not sure I agree with that, but it is a spectacular road that's very fun to drive a motorcycle on. It's a good two day trip, and Winthrop is a logical place to spend the night. Good food and lodging there. Nice side trips abound too, particularly the Twisp and Entiat river roads. If you go, check them out.
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