This Federal Home Owners’ Loan Corporation (HLOC) map of Baltimore from 1937 illustrates patterns of segregation that accompanied discriminatory practices in federal policy and the real estate industry operating in the 1920s and 1930s. (Shading refers to HOLC classes of mortgage worthiness: green, or A, was best; blue, or B, still desirable; yellow, or C, indexed definitely declining; and red, or D, was classed as hazardous for mortgage lending.)