In William Julius Wilson’s 1978 book, “The Declining Significance of Race,” the sociologist argued that racial discrimination was no longer the biggest barrier to black economic advancement. His fellow liberals were outraged. Forty-one years later, Mr. Wilson is still right and the political left is still in denial.

Accusations of white racism are all the rage in Washington these days. If you oppose school busing, you’re a racist. If you want immigration laws enforced, you’re a racist. If you’re against slavery reparations...