In 1928 Morgan went back to Louisiana to begin work on a proposed Longfellow Evangeline national monument at Bayou Teche in St. Martinville.
There he met faculty member and watercolor artist Gladys Butler (born 1899), whom he married on July 26, 1929, in McDonald County, Missouri.
For his daughter's tombstone Morgan designed a granite medallion, with a bas-relief profile of the girl and Celtic lettering, which is listed by the Smithsonian.
Through the span of his career Morgan had long-lasting friendships with Jules Bache, Bernard M. Baruch, Lincoln Borglum, Frances Elliott Clark and Jean Despujols.
Arthur C. Morgan died on September 9, 1994, in Shreveport, after which much of his work was reportedly thrown away or abandoned, though some was later recovered and put in storage.
Morgan, his wife Gladys and their daughter Cynthia are buried together in the same family plot at Forest Park East Cemetery in Shreveport.