And in the Democratic primary, an anti-eviction agenda is now practically a required element of candidates’ housing plans. Bernie Sanders supports a national “just cause” standard, limiting the grounds on which a landlord can evict a tenant. Cory Booker wants to prevent consumer reporting agencies from listing eviction cases won by the tenant. Amy Klobuchar wants to create new kinds of savings accounts that renters could tap in an emergency.

Such strategies most likely would not address the structural problems of sluggish wage growth and a scarcity of low-cost housing that underlie the eviction crisis. But they imply that even if eviction is a necessary remedy for landlords, perhaps there could be less of it.

“Sometimes you hear this response from property owners who say, ‘What do I do if a tenant is behind five, six, seven months?’ And that’s a really important question,” said Matthew Desmond, a sociologist at Princeton whose eviction research has influenced politicians. In data his Eviction Lab has analyzed from 22 states, that situation of tenants deep in debt is rare. It’s far more common, the lab has found, that tenants owe the equivalent of less than a month’s rent.

“That suggests a shallower end of the risk pool that you could lop off,” Mr. Desmond said.

Failure to pay rent is by far the most common cause of eviction. Across the 22 states where the Eviction Lab has data covering at least some counties, the median money judgment for cases between 2014 and 2016 was $1,253. Because that total includes other costs accumulated during the court process, most tenants initially faced eviction for the failure to pay a smaller rent sum (which is often not documented in eviction records).

Nearly half of the money judgments the lab has analyzed in Virginia were for less than the median rent in the census tract where the eviction occurred. In North Carolina, that’s true in more than 40 percent of cases. Across the 22 states, about a third of money judgments were for less than the local median rent.