According to a report by the McKinsey Institute for Black Economic Mobility released Thursday in honor of Black History Month, it could take more than three centuries for the gap between Black and white homeownership to close (320 years, to be precise). This means that Black Americans won’t have the same access to homeownership or lower rental burdens when compared to white Americans.

To close the gap sooner, according to McKinsey’s calculations, there would have to be a 20-year-long affordable housing plan, costing between $1.7 trillion to $2.4 trillion, producing 7.3 million units for low-income renters, most of which (4.5 million) would go to Black households.

“Effectively, there is nowhere in the United States where outcomes for Black residents equal those of their white neighbors,” according to the report. “Moreover, most places close to parity are small rural counties where outcomes are poor for all residents, regardless of race.”

Indeed, housing affordability affects Black residents more due to long-standing institutional and societal issues, Valerie White, senior executive director of Local Initiatives Support Corporation (LISC) New York, tells Fortune.

“It includes a mixture of access barriers, like racist practices in real estate and mortgage lending, and redlining, on top of the fact that Black Americans on average have lower pay than their white counterparts,” she says. This, “along with lower rates of generational wealth due to the obstacles established by hundreds of years of institutional racism that began with slavery, [continue] to perpetuate the disparities we see today.”

Communities where Black Americans reside

Almost nowhere in the U.S. are outcomes for Black residents equal to their white counterparts’, the McKinsey report shows.

“No U.S. county with a sizable Black population has achieved parity—or even come close,” according to the report. Indeed, less than 0.1% of the Black population actually lives in a county or city even close to parity.

About 30% of Black Americans live in megacities (the nation’s 12 largest urban centers), according to McKinsey, which is seven percentage points higher than the entire national average. These include New York City, Washington, D.C., Seattle, Houston, Atlanta, and Chicago. While these types of cities tend to have higher incomes and stronger job markets, they also have greater inequality and high costs of living, according to McKinsey, and more than 50% of Black residents in megacities have “outsize rent burdens.”

“Black residents of megacities outearn their peers at a national level but earn roughly 60% of what white megacity residents do,” according to the report. Plus, “the gaps in Black and white commute times are notable, showing that many Black residents have difficulty affording homes in convenient megacity neighborhoods.”

Another almost 19% of Black Americans live in what McKinsey calls “stable cities” like Pittsburgh, San Diego, New Orleans, Detroit, and Tulsa where median incomes tend to be lower (at $52,000). These places also rank poorly on health and longevity. Only 11% of white Americans live in stable cities.

Fewer Black Americans live in the suburbs (which McKinsey calls the “urban periphery”), which is about the only place where they tend to have better housing outcomes. Less than 12% of Black Americans live in these places, which is five percentage points lower than the total U.S. population. These are the places, however, where median household income, management roles, life expectancy, and bachelor’s degree attainment are higher. 

What’s more is that only 52% of Black suburbanites own their homes, compared to 78% of their white peers. While housing affordability is an obstacle to achieving homeownership, it’s not the only reason that Black Americans haven’t reached housing parity. Racist real estate practices such as appraisal discrimination, neighborhood segregations, and other institutional efforts to keep Black Americans from buying homes are also factors, White says.

“With all of these factors combined, and the institutionalization of racism embedded for generations, the options for Black Americans looking to purchase a home become extremely limited,” she says. “Disparities in education and literacy also make Black Americans vulnerable to predatory practices in banking, financing, and legal processes involved in home purchasing.”

Progress doesn’t mean parity

Achieving parity in housing isn’t going to happen overnight, but Black Americans did experience some improvements during the past decade. Black unemployment rates fell in stable cities, more Black Americans took on management roles instead of service roles, rent burdens fell, and incarceration rates dropped, according to the McKinsey report. Black Americans who live in rural counties also gained more broadband access, and megacities had more Black Americans with a bachelor’s degree. 

However, many communities saw Black homeownership decline and commute times rise. The pandemic also likely worsened labor force participation rates, lower preschool enrollment rates, and mental health, according to McKinsey.

“While Black outcomes improved over the decade in most of the counties in each segment, only about half of those counties narrowed the gaps between the overall scores of Black and white residents,” according to McKinsey. “In most community profiles, the racial gaps in some metrics barely budged.”

Racial housing discrimination has been perpetuated for generations, along with hundreds of years of institutional racism, White says, much of which still exists today.

“It makes complete sense that it could take generations to see true parity,” she says. “But that timeline could take even longer if more is not done collectively to address these disparities. Intentional and immediate action can fast-track the timeline outlined in the study, but inaction could more easily extend it.”