The road to Harts Pass and on to Slate Peak is the highest maintained road in Washington State. The drive is worth it. Once you get to the top of Slate Peak the panoramic views are quite spectacular. There aren't many places in the state you can see views like these without a long hike.
To get to Harts Pass, head to Mazama just one mile north of Highway 2. Once you get to the Mazama intersection, turn left and follow the road to the northwest. The pavement ends after about seven miles. From there it is about 12 miles of dirt road to Harts Pass, elevation 6198'. You will find a campground and Guard Station there.
I have read some accounts that say the road is unsafe to travel. I say hogwash. It's a great road. Much of it is a single lane with pullouts, so you won't be racing up it and passing cars along the way. But it's in good shape and can be traveled by any highway vehicle with reasonable clearance. Both times I've gone it has been on a street motorcycle. The first year my brother went up with his Prius. Check the conditions with the Ranger Station before going, though. There might be snow blocking the road part way up if you are too early or late in the season. Depending on the year, the road should be passable from early- or mid-July through September or October.
I can leave Edmonds around 9:00 in the morning and get to Mazama with plenty of time to drive over Harts Pass and on to Slate peak the same day and still get back to Mazama or Winthrop for dinner. It's not that far away...
The road is never steep, and mostly a good gravel road. There is one short section that is cut out of rock, and was a little rougher than the rest. Below, the road cuts through a section of trees that were burned by a forest fire a few years ago. (That's my brother's Prius out in front.)
Enjoy the view as you drive. Here the road passes through a meadow. This photo was taken August 2, 2010. It is still spring at this elevation!
But don't let the road lull you into inattention. It's safe to drive, but don't be careless. The one section that is cut through the rock has a "significant" dropoff along the edge. Look closely at this photo and you will see my motorcycle parked at a turnout. The photo doesn't do it justice. It's a long way down. And there aren't any guardrails.
Here I am at Harts Pass. The photo was taken facing the campground. The Guard Station is on the other side of the road from the campground, behind the camera.
The photo below was taken September 20, 2012, about a mile past Harts Pass. The larches have already turned color at this elevation. You can see the Pacific Crest Trail taking off to the north from the bend in the road.
Once you get to Harts Pass, you really must travel the remaining 1.8 miles to Slate Peak. The road is gated at the base of Slate Peak. Walk the remaining 1/4 mile to the top, elevation 7488', and enjoy the stunning views. Signs around the top of Slate Peak show the skyline and the names of the major visible peaks.
This photo was taken almost at the end of the road. You can see Slate Peak in the distance with the fire lookout on top.
So far I have been there twice - once in August, 2010, and once in September, 2012. In 2010 there was a lot of smoke blowing in from forest fires in Canada, which made the distant mountains difficult to see. I was hopeful in 2012, but a week before I went a major lightning storm traveled through eastern Washington that started many forest fires, and smoke from those fires partially obscured the mountains. Guess I'll have to make another trip...
Harts Pass Locator Map