We honor Dr. Martin Luther King Jr. with a national holiday because he was a transformative leader whose words and actions advanced a vision of the nation as it should be — one in which all people have equal opportunity. But too few people realize just what a huge role housing plays in this legacy — or that these hard-fought protections are now under threat.

The Fair Housing Act, a landmark housing bill championed by Dr. King despite fierce opposition, was enacted in April 1968, a week after his assassination. Its goal was to ensure that everyone can choose where they want to live, free from systemic discrimination. This was the final major legislative achievement of the civil rights era, and one which sought to address decades of segregative policies and practices.

Now, the U.S. Department of Housing and Urban Development, under Secretary Ben Carson, is weakening fair housing protections that help build inclusive communities. In addition to scaling back most high-priority fair housing investigations and enforcement activities, HUD suspended a key rule that requires local governments to affirmatively further fair housing by assessing and addressing barriers to housing opportunity in their communities. HUD has also announced plans to revise an important tool in fighting systemic discrimination, the disparate impact rule.

All of these protections remain crucial. Our segregated communities are the result of decades of intentional government policies. People of color were long denied federal homeowner resources given to white families, and the use of redlining undermined real estate values in black neighborhoods, creating areas of concentrated poverty that still exist today.

Recent data from the census and research from the Urban Institute show that black homeownership rates have declined to levels not seen since the 1960s. More than one in every four black Americans and one in every six Latino Americans lives in neighborhoods marked by extreme poverty, compared to one in 13 white Americans, according to a 2015 Century Foundation study.

Housing discrimination affects us all, and the problems created by segregation and inequity ripple out to destabilize local economies. A 2017 report by the Metropolitan Planning Council and partners found that "if the Chicago metro area were less segregated, it could see $4.4 billion in additional income each year, reduce the homicide rate by 30 percent and issue 83,000 more bachelor’s degrees."

“The problem of housing discrimination is a glaring reality all over this country, north and south,” Dr. King said in 1964. “And as long as we have this problem, there will be some form of de facto segregation in the public schools and in all other areas of life.”

I know firsthand that realizing Dr. King’s vision will take hard work. To become the nation envisioned by Dr. King, we must all defend the Fair Housing Act and the rules that strengthen it. Sharon Legenza is executive director of Housing Action Illinois, a statewide coalition that has led the movement to expand affordable housing in Illinois for more than 30 years.