The Ring-billed Gull (Larus delawarensis) experienced a significant contraction of its range from the Great Lakes eastward during the nineteenth century, but it staged a remarkable recovery in the late twentieth century that continues to the present. A rapid increase in population size in Maine, indexed by Christmas Bird Counts and field sighting data, occurred from the early 1970s through the 1990s. The timing of population growth in Maine closely paralleled the growth and spread of breeding populations along the St. Lawrence River in Québec, and eastward into the Maritimes. At this time, Ring-billed Gulls also began to appear in greater numbers during summer on interior lakes in Maine. Breeding colonies are now known on two inland lakes.