From Jordan Valley, Oregon southward to McDermott(on the state line between Oregon and Nevada) , the speed limit is 55, and it’s inadequately posted. If you’re driving north from McDermott to Jordan Valley, there are two "55" signs as you leave the outskirts of McDermott. For the rest of the long drive north to Jordan Valley, you won’t see a speed sign, although there are many signs that say "passing zone" and "no passing".
The same road crosses through Nevada and is posted at 75 and 70, with some of the same conditions. So you drive north through Nevada at 75, then cross the Oregon border at McDermott and have to slow to 55 for the next 90 miles.

The neighbor states, Nevada, Idaho and California, all post speed limits often and with many different speeds, to account for road hazards such as curves, hills and narrow sections. Oregon does not; they just post the speed limit at the edge of town as you start out, and that’s it.