In the U.S., outsider art had a different trajectory. Ground zero wasn’t the psychiatric wards, but rather the South. One of the first American self-taught artists to reach star status was William Edmondson (1874–1951), the son of former slaves, who, after losing his job as a hospital orderly in Nashville, had a vision that set him on his course: “I was out in the driveway with some old pieces of stone when I heard a voice telling me to pick up my tools and start to work on a tombstone,” he recalled. “I looked up in the sky and right there in the noon daylight He hung a tombstone out for me to make.”

Like Wölfli, Edmondson was lifted into the world of high art by a chain of insiders—in his case, a Vanderbilt professor named Sidney Hirsch, the photographer Louise Dahl-Wolfe, and finally Alfred H. Barr Jr. of the Museum of Modern Art, which gave Edmondson a solo show, the first there for an African American artist, in 1937. Edmondson’s ascent was unusually quick.

More typical was the slow rise of Bill Traylor (c. 1854–1949), whose spare, off-center drawings of humans, animals, and “Exciting Events” on scraps of used cardboard are now outsider classics. (The American Folk Art Museum currently has two shows devoted to him.) Traylor, also the son of slaves, had a long trip (mostly after his death) to the pantheon. In 1939, when he was an old man drawing on the streets of Montgomery, Alabama, he met Charles Shannon, an artist six decades younger. Shannon was enthralled with Traylor’s ways: “He never agonized over his work … He was very serene. He rarely erased.”

Shannon did his best to get Traylor national recognition. But it didn’t come until long after Traylor died. In 1982, Traylor was featured in the Corcoran Gallery of Art’s landmark exhibition Black Folk Art in America: 1930–1980, organized by Jane Livingston and John Beardsley, which also included Sam Doyle, David Butler, and Sister Gertrude Morgan.

This was the birth of the American self-taught canon, launching the fortunes of 20 outsider artists. The funny thing was, many of these artists were already well-known figures in their own towns—hardly outsiders, as Livingston observed. If they had been, she said, “we would never have found them.” (Which raises a conundrum: if an outsider paints in the forest and no one sees him … )

You may be wondering why Henry Darger, the most famous outsider of all, has hardly been mentioned. In 1973, Darger died, leaving behind in his cramped room his illustrated magnum opus, The Story of the Vivian Girls, along with bottles of Pepto-Bismol, balls of string, coloring books, ads featuring the Coppertone girl, and his daily weather logs.

Forty years later, Darger is the uncontested poster boy for outsider art. The American Folk Art Museum has a study center devoted to him and has presented numerous shows, including one titled Dargerism, about his influence on other artists. MoMA PS1 had a show comparing Darger with Francisco de Goya and with the contemporary artists Jake and Dinos Chapman. A biography by Jim Elledge, Henry Darger, Throw-Away Boy: The Tragic Life of an Outsider Artist, has just been published. But Darger isn’t in the Biennale. Nor was he in Great and Mighty Things. Or in the Hayward show. Is Darger in danger of being ejected from the outsider circle for being too much of an insider?