US Highway 630 was the sixth “child route” of the transcontinental US Highway 30 and was commissioned in 1927. At that time, it was the shortest US highway in the system, coming in at only a mere three miles in length. It was apparently designed to serve as a connector between US 30 in Oregon and US 95 in Idaho.
The route began at a junction with US 30, some fifteen miles north of Ontario, Oregon. There, as US 30 turned westward, US 630 continued north and crossed the Snake River into Idaho, and ended at a junction with what was then the south beginning of US 95 in Weiser.
The US 630 designation lasted only six years; by 1933 it had been decommissioned, though maps from the era don't indicate whether its routing was taken over by US 95, or by US 30N, a then-existing spur of US 30. Today, the highway still serves as a connector, to Interstate 84, and carries the designation of Spur US 95.
Droz, Robert V., "Sequential List of US Highways", US Highways From US 1 to US 830
. July 2003. <http://www.us-highways.com/us1830.htm> (February 2009)
Sanderson, Dale. "Highway Ends", End of Historic US Highway 630
. 21 July 2005. <http://www.geocities.com/usend3039/End630/end630.htm>. (February 2009).