In the short time since Kamala Harris and Joe Biden tangled over the history of busing in the first Democratic primary debate, the question has awkwardly shifted to the present.

Busing is still needed today, Ms. Harris has since said. But discussion of just what that would look like has appeared to make both candidates uncomfortable on the campaign trail. As the issue lingers, it is easy to imagine a future debate question — one of those raise-your-hand episodes: “Do you support busing today?”

That is not the right question for this moment, according to researchers who’ve studied school desegregation and what happened when those efforts waned across the country. The term “busing” itself remains loaded in the same way it was in the 1970s. And the deeper problems that policy sidestepped remain largely unresolved today, with many school systems more segregated nowthan they were under court-ordered integration plans.

“The question is not, ‘Do we say yes or no to a 1970s-through-1990s intervention?’” said Ansley Erickson, a historian at Columbia University. “It’s ‘What is the intervention we need right now?’”

We know that schools and communities are segregated today because of past actions, in part those taken intentionally by the government, she added. What’s the obligation of the president today, she would also ask each candidate, to address that?