Little is known about pre-contact Indigenous agronomic practices in northeastern North America. While there is historical documentation from the early 20th century A.D. of field remnants, only a few have been subject to archaeological investigation. Recently obtained stable nitrogen isotope ratio measurements (15N/14N or δ15N) on charred maize (Zea mays ssp. mays) kernels have led to new insights on pre-contact Iroquoian agronomy. Here, we extend that analysis to the Burnham- Shepard and Morgan sites in Connecticut, two key late pre-contact Algonquian sites in the Connecticut River Valley. Results of δ15N on maize kernels recovered from these sites indicate nitrogen was not a limiting factor for maize in the sites’ agricultural fields. New AMS dates on maize and other annual plant structures revise the occupational chronology of both sites.