North Cascades Highway — Marblemount to Winthrop: Washington Driving Guide

The drive

This WA 20 segment starts in Marblemount and crosses the North Cascades toward Winthrop. It excludes the longer Clear Lake approach in the third-party discovery GPX and is not the full Cascade Loop.

The distance shown is measured along this specific connected road trace. It excludes your approach to the starting point, sightseeing spurs and any return journey. Inspect the endpoints and map before deciding whether it fits your trip.

This is an untimed planned road itinerary reconstructed from licensed OpenStreetMap road nodes, not a recording of a completed drive. Road-node connectivity and mapped driving direction have been checked; live access, unmapped restrictions and road-surface conditions are not guaranteed.

RevScore: this route's curviness

How these planning facts were checked

The OSRM car-routing model was checked against 100 points along this exact GPX, including its loop or segment shape—not simply the fastest route between the endpoints. The 2 h 25 min–3 h 40 min range uses rounded planning allowances of 15–75% above the model's no-live-traffic baseline. These allowances are not measured traffic statistics or a guarantee; allow extra time for lunch, photographs and other stops.

Terrain elevations were sampled at 141 points along the GPX using the USGS NED approximately 10-metre terrain dataset hosted by Open Topo Data (dataset snapshot: April 23, 2020). The displayed range is rounded to 50 feet / 10 metres. It is an approximate sampled range—not an exact road minimum/maximum, summit height or cumulative elevation gain. Terrain can differ from the road surface around tunnels, bridges and road cuts.

Facts checked October 21, 2026. Sources are linked under “Guide sources.” The original GPX remains an untimed map trace; these modeled facts are not recorded-drive measurements.

Driving notes

1. Respect road users and local communities

   Observe posted limits, allow safe passing and use designated stopping places. RevScore describes route geometry; it is not an invitation to drive faster.

2. Inspect the exact segment

   WA 20 in Marblemount to WA 20 in Winthrop. A matching road name alone does not mean a downloaded file covers every part of the road.

Places along the route

• WA 20 in Marblemount

  Mapped starting area; arrange legal parking and supplies separately.

• WA 20 in Winthrop

  End of this one-way trace. Plan onward travel or a return separately.

Cautions

• Check official access before departure

  The mountain crossing normally closes for winter because of snow and avalanche risk. Reopening is weather dependent, not guaranteed by a calendar date. Check WSDOT for the exact closure limits and current access before departure. Fuel and services are limited across the pass corridor.

Questions drivers ask