Sepia postcards were printed in a brown colour instead of black inks, and went in and out of fashion from the early 1900s through the 1940s. Although mailed in 1938 and probably printed that decade (Tucks cards had a very long life), this type of Tuck card goes back to the early 1900s.
[Verso] Postmarked March 4, 1938, mailed to "Bobbie McGeary, 26 S [?] Dudley, Westfield, M.G. U.S.A. Hello to everybody Hope all is well as we are L[ove?] M & D"