FDR Lake was created by America's most powerful electricity generating plant on this river, whose longest tributary [emphasize] flows through Jackson Hole and Hells Canyon before joining it and the Yakima at Pasco.
This river takes a 180-degree turn where it joins the Canoe at the site of Boat Encampment, from where the York Factory Express followed the path of this river downstream. The rocky terrain around this river's mouth has prevented the formation of a delta, so its unimpeded flow hits a sandbar at its mouth at Cape Disappointment. This river flows through the Tri-Cities area, passing by the cities of Richland and (*) Kennewick. FDR Lake was created by America's most powerful electricity generating plant on this river, whose longest tributary [emphasize] flows through Jackson Hole and Hells Canyon before joining it and the Yakima at Pasco. The Grand Coulee Dam straddles this river, which is joined by the Willamette at Portland. For 10 points, name this river in the Pacific Northwest that forms the border between Washington and Oregon.
This river takes a 180-degree turn where it joins the Canoe at the site of Boat Encampment, from where the York Factory Express followed the path of this river downstream.
Columbia River 