Reflecting on her early years in Washington, Gilliam recalled taxis refusing to pick her up, colleagues failing to acknowledge her outside of work, and being told to use the maid's entrance while reporting on a story. Gilliam used these experiences to promote change and inclusivity in the journalism field later in her career.
In 1962, Gilliam covered the integration of the University of Mississippi for the Post. She reported on how the historic event impacted the Black community while sleeping in a funeral home, as nearby hotels would not accommodate Black journalists.
Gilliam worked at the Post City Desk for five years until resigning to raise her children. She returned to the Post in 1972 as the Style section’s first Black woman reporter. She kept the position for several years before being promoted as the Post’s first Black woman columnist.