A week after the assassination of the Rev. Martin Luther King Jr., the landmark Fair Housing Act was signed by President Lyndon Johnson. The act, now 50 years old, outlawed discrimination based on race, color, national origin, sex or religion in housing sales, rentals or brokerage services. It was the last of the three great federal civil rights acts passed in the 1960s, including the Civil Rights Act of 1964 and the Voting Rights Act. Nonetheless, de facto housing segregation in communities in the United States remains prevalent, numerous studies have found.

“We honor these two moments in our nation’s history by continuing to confront overt and even subtle discrimination that persist half a century later,” wrote Ben Carson, secretary of the U.S. Department of Housing and Urban Development, in an opinion piece published Tuesday in USA Today.