Washington Hwy 20 then 155 to Grand Coulee Dam

Not unless there is early snow. I love Hiway 20.

The only problem is you are doing it and I'm not.

Fuel!
Make sure you fill up at Sedro Wooley as there is virtually none until you get to Winthrop.

enblethen wrote:
Fuel!
Make sure you fill up at Sedro Wooley as there is virtually none until you get to Winthrop.

There is gas at Marblemount. and at Mazama.

Never gas up in Concrete, price is too high.

gas at the reservation on 20 or I-5

Marv Hoag wrote:
This is the route I am planning to take in September from Fidalgo Island. Any problems with this route?

No, that's the way we go. or use the directions below, we gas on the way out at the res.

when you leave Twisp, use 153 south to Parteros, intersect with 97 go north to Brewster cross the river and use 173 to 17, then 174 to Grand Cooley.
It's good road and shorter than 97 to 155 plus hwy 20 over Loup Loup pass is pretty nasty curvey highway.

In Brewster turn right at the IGA store, right again at bridge street. that will cross the river. turn left at the east end of the bridge to Bridgeport. that will be 173.

Pateros and Brewster have fuel

If you are traveling alone, I'd not use 155 across the Coalville Indian res. it is a long lonely road.
and why go way up to Omak then back down to Grand Cooley.

I would not like to buy fuel at Mazama. It use to be quick expensive. Don't remember having diesel!

enblethen wrote:
I would not like to buy fuel at Mazama. It use to be quick expensive. Don't remember having diesel!

Like Marblemount, it is expensive, but it is there.

You'd have to get horrible gas milage to not be able to go from the I-5 area. to the rt. 97 area, even my jeep will do that.

Fuel is not a problem. Fill up on Fidalgo Island and I can go all the way to Spokane, no problem.

According to Google Maps, the route via 155 is just a bit shorter than the one via Pateros, and time is about the same.

You may need to set your departure date to a summer one, since WA20 is closed right now, and GM might not give you a route through Winthrop.

I haven't had a sense that 155 is any more remote (or dangerous, in what ever sense?) than 17. Overall the north route might stay a bit higher, but the south one drops lower, at the Bridgeport river crossing. I've even taken the Columbia River Road, which skirts Omak Lake and the north shore of the River downstream from the Dam.

But speaking of grades, you could switch the route means to bicycle and see a route profile.