The Snake River
The Rio Grande
That would be Oregon
Yes, Idaho does have a panhandle. It forms the northwest portion of the state, and borders Canada on the north and Washington (and Oregon) on the west.
Columbia River, Oregon.
Columbia river
michigan
Columbia river
Yes, the Columbia River forms the boundary between the states of Washington and Oregon for most of its length. It serves as a natural border between the two states as it flows from the interior of the Pacific Northwest out to the Pacific Ocean.
The Snake river flows east for part of its course and the water eventually flows into the Pacific Ocean. It forms part of the border between Idaho and Oregon The Columbia river forms most of the border between Washington and Oregon, but the water in it flows WEST, so unless you meant something like "runs in an east-west direction" the Columbia is not the river you are looking for.
The Columbia River.
The Columbia River.
The Columbia River.