The gull Larus smithsonianus Coues, 1862 was based on specimens in the collections of the Smithsonian Institution, but no type material has been identified and the type locality was never restricted beyond the eastern and western coasts of North America. We here designate USNM 18216 as lectotype, and the restricted type locality thus becomes Henley Harbour, Strait of Belle Isle, Newfoundland Labrador, Canada. It is proposed that Larus smithsonianus be treated as specifically distinct from the Old World Herring Gull Larus argentatus and take the English name Smithsonian Gull.