Later in the 1880's, Mannheim emigrated to the U.S., settling in Chicago where he was a portait painter, and also an art teacher in the downstate town of Decatur. From there, he went to London where he taught for two years, and after returning to the U.S. and teaching art for a brief time in Denver, he settled in Pasadena in 1908 and built a home on the rim of the Arroyo Seco.

In Southern California, Mannheim developed the bright style of painting landscapes for which he is best known. In Pasadena, he continued his interest in teaching art by establishing the Stickney Memorial School of Fine Arts in 1913. Over his four decade long career, he was exhibited widely, received numerous awards. His paintings are in the Oakland Museum, the Irvine Museum and the National Portrait Gallery in Washington, D.C. Sources: AskArt.com, Artists in California 1786 - 1940, Edan Milton Hughes, 3d ed.