During the late 1920s and 1930s, Leighton visited the United States on a number of lecture tours, emigrating to the US in 1939. In 1930, the
Art Institute of Chicago awarded her with the Mr. And Mrs. Frank G. Logan First Prize ($100). She lived in
Baltimore for a while and became friends with
H. L. Mencken. Leighton became a naturalised citizen in 1945. From 1943 to 1945 she was a member of the Department of Art, Aesthetics, and Music at
Duke University. In 1945 she was elected into the
National Academy of Design as an Associate member and became a full Academician in 1949. Over the course of a long and prolific career, Leighton wrote and illustrated numerous books praising the virtues of the countryside and the people who worked the land. In 1932, she was the first woman to produce a book on wood-engraving,
Wood-Engraving and Woodcuts. This played an important part in popularizing the medium. During the 1920s and 1930s, as the world around her became increasingly technological, industrial and urban, Leighton continued to paint rural working men and women. These included a 1938 poster design for
London Transport promoting weekend walks in the countryside. In the 1950s she created designs for
Steuben Glass,
Wedgwood plates, several stained-glass windows for churches in
New England and for the transept windows of the
Cathedral of Saint Paul (Worcester, Massachusetts). Three of Leighton's woodcuts for
H. R. Williamson's
The Flowering Hawthorn (1962) were selected by Adam Stout to illustrate his 2020 book on the Glastonbury Thorn. Several of Leighton's prints were included in the 2025
Clark Art Institute's exhibition
A Room of Her Own: Women Artists-Activists in Britain, 1875-1945. ==Personal life==