Mr. Trump has performed well thus far in Appalachian coal counties and in rural parts of Alabama and Mississippi, which are coping with economic and social dysfunctions like high unemployment rates and heroin addiction. But the Upshot analysis also shows the common thread between those places and more urban locations where Mr. Trump has either done well or is projected to.

In Revere, Mass., a working-class suburb of Boston, Mr. Trump won 73 percent of the Republican primary vote. The New York Times’s model suggests he will perform strongly on Long Island when the New York primary takes place April 19 and in Ocean County, N.J., on the Jersey Shore, during voting on June 7.

There were only weak correlations between Trump support and various measures of economic performance from 2007 to 2014, including the lingering damage from the 2008 global financial crisis. Rather, the economic problems that line up with strong Trump support have long been in the making, and defy simple fixes.

The high proportion of whites without a high school diploma in these places — the single strongest predictor of Trump support of those we tested — has lasting consequences for incomes, for example. The education pay gap starts small when people are early in their careers before widening over the decades of their working lives. College graduates are less likely to become unemployed and more likely to find a new job quickly if they do, and there are comparatively fewer of them in Trump-land.

In places where Trump does well, relatively high proportions of workers are in fields that involve working with one’s hands, especially manufacturing. The decline in manufacturing employment is not a story of merely a rough few years for the economy; nationwide factory employment peaked in 1979, and as a proportion of total jobs has been declining almost continually since 1943. Forces including mechanization and trade have put employment prospects in the sector in an ever-worsening position.

Likewise, a better predictor of strong Trump support than a standard-issue economic indicator like the unemployment rate is a high proportion of working-age adults who aren’t working (the correlation was strong for both men and women).