This first-cycle gull was photographed at Galveston County Landfill, Texas, on January 26, 2006: I presume it to be a dark American Herring Gull Larus [argentatus] smithsonianus, but I am struck by how many Western Gull features it has...?:
Note the secondaries extending beyond the coverts, and the pattern of the greater secondary coverts:
Note the obvious white trailing edge to the secondaries, the subdued panel on the inner primaries, and a tail that lacks any barring in the outermost feathers save for some thin white "dashes" along the extreme outer edge of each outermost tail feather:
Features that argue against Western Gull include the overall darkness of the uppertail coverts, and the pattern of 2nd-generation upperpart feathers.