Harriet Cosgrove (1877-1970) became fascinated by the archaeology of the Southwest when she moved to Silver City, New Mexico, 1906. Silver City had been established near the ruins of pre-Columbian Mimbres culture which flourished from a.d. 200 to 1150. During the early years in New Mexico, Harriet, her husband, Burton, and son, Burton Jr,. spent much of their spare time exploring the Mimbres Valley.
In the 1920s the Cosgroves met A. V. Kidder who was Curator of North American Archaeology at the Peabody Museum and a key player in the burgeoning field of Southwestern archaeology. Kidder was impressed by the Cosgroves' amateur excavations and through his efforts the Cosgroves were hired by the Peabody Museum in 1924 to excavate the Swarts Ranch Ruin, a Classic Mimbres site (a.d. 1000-1150). Thus began a long-term association with Kidder and the Peabody Museum.
The work at Swarts established the Cosgroves among the elite of Southwestern archaeologists and reinforced their identity as a team. The work at Swarts was prodigious. Burton photographed the site. Harriet made pen and ink drawings of every bowl excavated and recorded every find in a series of field notes maintained for each season. The thoroughness of the field notes is astounding. Harriet described every room, its location, dimensions, and soil type. She recorded every artifact and described every burial. Published in 1932, the final report is still the primary reference for Mimbres scholars.
Their success at Swarts was a springboard to other work: they worked in the Gila River of New Mexico in 1928-1929 and in late 1929 with William H. Claflin Jr., of Belmont, Massachusetts at Stallings Island Mound in Columbia County, Georgia. Their next major project (1936-1939) was at the Hopi Pueblo of Awatovi in Arizona which was excavated under the direction of J. O. Brew (Director of the Peabody Museum from 1948-1967). Burton died during the first year of the project, but Harriet returned to Awatovi in 1937. She was in charge of the pottery tent for the duration of the Awatovi project and trained student and Indian assistants in washing, sorting, and cataloguing the artifacts.