The chicken was among the first domesticates introduced to North America by European explorers, and they quickly became established in the New World. Morphometric analysis of chicken remains from sites in eastern Canada and the Northeastern United States demonstrate that the founding population of chickens was morphologically diverse, likely representing several different types of chicken. Further comparison of these data with those from medieval and post-medieval sites in England reveals that ongoing selection for larger body size in both populations did result in larger chickens, but that the physical proportions of these birds remained relatively consistent across time and space until the 19th century, when breeds were codified and breeders began producing specialized laying, broiler, and show birds with increasingly exaggerated characteristics.