The most widespread pink-legged gull in North America, the herring is common in the east and mainly a winter visitor in the west. Hybrids can be locally common (mainly in the wescat). Polytypic. Length 22–27"; wingspan 53.5–60".

Large gull with 4 plumage cycles; sloping head and fairly stout bill with distinct (but not bulbous) gonydeal expansion. Pink legs at all ages. Subspecies smithsonianus described unless otherwise noted. Breeding adult: pale gray upperparts; black wing tip with white mirrors on outer 1–2 primaries. (In West, most have mirror only on outermost primary.) Pale-yellow eyes (can be dusky, especially in west); yellow-orange orbital ring; yellow bill, reddish gonys spot. Winter adult: dusky streaking and smudging on head and neck. Duller bill and legs;