Jacob Lawrence painted “The Migration of the Negro,” 60 small pictures in tempera on hardboard panels, in what seems like a flash. The series was completed in 1941, after about a year of work in a cold-water studio at 33 West 125th Street in Harlem. Lawrence was 24. With its visual tact and deep emotion, it was instantly recognized as a tour de force, a new American epic. It made his career.

The series is about the shift of African-American populations from a poor and repressive rural South to a prosperous but unwelcoming urban North between the two world wars. Lawrence’s family participated in that shift. For him it was lived history, an organic phenomenon, and he conceived his depiction of it that way. But two concurrent exhibitions — one at the Whitney Museum of American Art, the other at Triple Candie, a nonprofit space in Harlem — suggest that his concept has not come down to us intact.

Lawrence painted the 60 pictures not one at a time but production-line style, working on them all simultaneously. In a given studio session he would apply a single color to several paintings in progress. In the next session he would apply another color in the same way. Chromatic recurrence was one way he bound the series together....