Twenty-four years elapsed between Carr's master's degree and her Ph.D., because she left Harvard in 1947 after getting married and moving to New York.[2][3] She later moved to Maryland, divorced and remarried, and started a new thesis on Maryland history, finishing her doctorate in 1968.[3] She had one son from her first marriage, Andrew R. Clark.[1]
Carr started as a junior archivist in 1956 at the Maryland State Archives in Annapolis, becoming a senior adjunct scholar in 1988.[4] She became the historian for Historic St. Mary's City in 1967, founding a research program seeking to document the lives of every known 17th-century St. Mary's resident.[1][4] She was president of the Economic History Association in 1990–91.[5]
Carr was an adjunct professor of history at the University of Maryland, College Park from 1982 to 2005.[2] She was a pioneer in the field of colonial history, designing and directing several long-term team history research projects that won support from the National Science Foundation and the National Endowment for the Humanities.[5] In 1992, the a conference was organized at the University of Maryland in her honor, Lois Green Carr: The Chesapeake and Beyond - A Celebration.[6]
Carr was a co-author of Robert Cole's World: Agriculture and Society in Early Maryland, which won the Alice Hanson Jones Prize from the Economic History Association in 1992 and the Maryland Historical Society Book prize in 1993.[6] She was one of the 1996 recipients of the Eisenberg Prize for Excellence in the Humanities.[7] In 2000 she was named to the Maryland Women's Hall of Fame.[1][6]
