Crack is Wack is arguably Keith Haring's best-known work. It might also be the most famous mural in New York City. For one, it probably has more daily views than any other mural in NYC, due to its location next to passing cars on the Harlem River Drive (in Manhattan at 128th Street).
How Crack is Wack came to be is not well-known. Nor is the fact that the mural is not the original version.