For centuries, the most important ways that art reached millions was through illustrations for magazines and books. I was just a little kid when I saw a library book with the most beautiful illustrations I'd ever seen. Although I've long forgotten the title and author of the book, I do recall the awe I experienced at the art.
In fact, some of the beloved artist, who touched others, were illustrators such as Norman Rockwell, Beatrix Potter, N.C. Wyeth and Maurice Sendak. One that you might not be as familiar with is Frank Schoonover (1877-1972) although he was a very prolific illustrator.
Beyond Schoonover's many illustrations for magazines and books, he created over 5,000 paintings! His time marks the early 20th century regarded as the "Golden Age of Illustrations."
His illustrations included swashbuckling figures for adventure books, cowboys and mavericks for western books and even the sad situation of soldiers during WW1.
In addition to Schoonover's own works, he collected and saved the works of other illustrators plus he taught art in his own studio.
In case you think he's a forgotten illustrator in the scheme of popularity, there is the Schoonover Studio in Wilmington, DE. It was started as a studio and school by Howard Pyle, but soon outgrew the building.
It was the efforts of Schoonover and others to find a philanthropist to finance an expanded school. Among the illustrious attendees of the new school included N. C. Wyeth.
You don't have to go to Delaware to see the famous school for illustrators. In keeping with modern times, there's a YouTube of Schoonover's grandson being interviewed about the studio. Just type in "Frank Schoonover."