During his career Sandzén created a copious amount of artwork: over 3000 paintings and watercolors, almost 100 sketchbooks, along with an extensive body of lithographs, work cuts, and drypoints numbering in the tens of thousands.
Library of Congress, Washington D.C.
Chicago Art Institue, Chicago, IL
Denver Art Museum, Denver, CO
Museum of Fine Art, Santa Fe, NM
Brooklyn Museum of Art, New York City, NY
Taos Society of Artists
Prairie Water Color Painters
New York Water Color Society
Philadelphia Water Color Society
Mid-West Art Exhibition (founder)
Prairie Print Makers (charter member)
Society of American Etchers, Gravers, Lithographers, and Woodcutters