The settlement Baltimore County Executive Kevin Kamenetz announced yesterday with the federal Department of Housing and Urban Development represents an unprecedented acknowledgment by the county government that it must play a role in ending the racial and economic segregation that have for a century trapped thousands in communities defined by extreme poverty and lack of opportunity. Mr. Kamenetz's willingness to embrace the issue is laudable considering the county's shameful history when it comes to efforts at integration — including but certainly not limited to the ugly backlash against the Moving to Opportunity program in the 1990s.

That program was minuscule — a pilot effort begun under the first Bush administration that would have allowed a whopping total of 285 families to move from concentrated areas of poverty in Baltimore City to better neighborhoods throughout the region. But its legacy looms large in any conversation about integrationist housing policies in the suburbs. The county has gotten substantially more diverse since then — it was 90 percent white in 1990, compared to about 64 percent now — but the population of opportunistic politicians willing to stir resentments along racial or economic lines remains undiminished. The alarm raised in December after The Sun revealed a quiet program through which a few dozen low-income Baltimore families have been relocated to the suburbs — and not just in Baltimore County — is testament to that. We shudder to imagine the rhetoric that's coming now that Mr. Kamenetz has agreed to subsidize the construction of 1,000 affordable housing units in “high opportunity” neighborhoods over the next decade.

But the sad reality is that 1,000 units barely begins to address the need. In 2014, the regional Opportunity Collaborative found a deficit of 70,000 affordable homes in the Baltimore region, a circumstance that traps the poor in increasingly desperate conditions in neighborhoods with little access to jobs or transportation. And the effects are stark. Last year researchers at Harvard reported that Baltimore was the worst of the nation's 100 largest counties (or, in our case, county-equivalents) when it comes to a child's chance to escape poverty. Every year of childhood spent in the city reduced eventual lifetime earnings by 0.86 percent compared to an average county. The effect was even worse for boys. The researchers also showed that while Moving to Opportunity didn't have much effect on parents' income, it was strikingly positive for children who moved to better neighborhoods when they were young.

That's why the second piece of the county's settlement with HUD is so important. Mr. Kamenetz has agreed to introduce legislation banning so-called source-of-income discrimination, meaning that landlords would no longer be able to reject tenants simply because they use federal Section 8 vouchers to pay part of their rent. Of course, introducing such a bill is a far cry from seeing it become law; the County Council has shown no willingness to enact it and not much support for affordable housing generally. HUD seems to have anticipated this, as the settlement calls for Mr. Kamenetz and his successors to re-introduce the legislation as many as a dozen times until it passes, an equivalent state law is enacted or the term of the agreement expires.

The settlement obligates Mr. Kamenetz to take steps to promote the bill's passage, such as supporting it in the media and public forums. We urge him to take that requirement seriously. He has displayed a commitment to tackling issues like this on a regional basis that is unusual by Baltimore County executive standards, for example by starting to set aside money to subsidize the development of affordable units well before this agreement required it. But it hasn't won him many friends — indeed, it's hard, given the reaction, to understand his critics' claim that he's just doing things like this to support an ambition for higher office.

There are some concrete steps he could take. Some landlords have objected to legislation like this in the past on the grounds that they don't want to deal with the bureaucracy involved in renting to Section 8 recipients. The county should look for ways it can help mitigate that concern. More broadly, Mr. Kamenetz needs to make the case that taking these steps is in the county's interest — and not just because of the legal consequences if it fails to keep up its end of the bargain. Baltimore County has its own pockets of concentrated poverty, and it runs the risk of seeing them grow if it doesn't work to ensure more socio-economic diversity throughout its communities.

When the poor and minorities are given the opportunity to live in more prosperous communities, we all reap the benefits in terms of a more vibrant, dynamic economy and lower social costs. When they are segregated in islands of poverty, we all pay the price.