... Mr. Trump’s rhetoric resonates with a particular American political tradition. Voters may not know the details of that tradition, but they feel it viscerally when a politician taps into it. Mr. Trump has done just that by emulating a classic model of American democratic leadership.

A clue as to just which leadership model can be found on a map. While Trump fans are spread across the country, they are heavily concentrated in and near the Appalachian states — from Mississippi and Alabama all the way to western Pennsylvania and New York. The northwest corner of South Carolina is one of the most pro-Trump parts of the country.

Greater Appalachia has remained culturally distinct for centuries. Migrants from the northern British Isles — Scots, Scots-Irish and others — pushed into these mountains in large numbers from the 1700s onward and did much to create the nation as we know it. Their descendants weathered generations of hardship and calamity: washed-out hillside farms, coal-mining disasters and extreme poverty.

Though today’s Appalachia also features excellent roads, shining auto factories and fresh waves of migration, its electorate represents an older version of America, more rural, white and conservative than elsewhere. To live or work in Appalachia is to feel the tug of its past.

What could the voters of such a region possibly see in a loud and self-interested New York real estate tycoon? In some respects, he is a type of leader Appalachia has seen before. Students of history will recognize that Mr. Trump is a Jackson man.