There are plenty of fine 20th c. artists - George Bellows ("Stag at Sharkey's"), Rockwell Kent (a d***ed commie but he was good), Reginald Marsh (a favorite of mine - Hopper with spirit and affection), Harvey Dunn (another favorite - a regional Dakota artist), Grant Wood of course, Thomas Hart Benton. And N.C. Wyeth, especially for his easel work. Like Rockwell, he got pigeonholed as an "illustrator" but had serious talent. Andrew is more popular now but he's not up to N.C.