Look at county-level maps of almost any closely contested presidential race in our history, and you see much the same fault lines: the swaths of the country first colonized by the early Puritans and their descendants — Yankeedom — tend to vote as one, and against the party in favor in the sections first colonized by the culture laid down by the Barbados slave lords who founded Charleston, S.C., or the Scots-Irish frontiersmen who swept down the Appalachian highlands and on into the Hill Country of Texas, Oklahoma and the southern tiers of Ohio, Indiana, Illinois and Missouri.

The Quaker-founded Midlands, the swing region of American politics that makes up a great swath of the heartland, has often been the physical and political buffer between rival regional coalitions, its pluralistic, community-oriented culture at peace neither with the Yankee’s utopian drive to engineer social improvements nor Southern culture’s emphasis on individual freedom above all else. It played the kingmaker’s role again in 2016.

Pundits speak of the “solid South,” but Yankeedom has had stalwart allies as well. The people of the slender Pacific coastal plain from San Francisco to Juneau, Alaska, have backed the same horse as the Yankees in virtually every contest since their states joined the union, and in opposition to the candidate favored by the majority of people in the interiors of their own states. Yankees have long found partners in the Dutch-founded zone in and around New York City and, in recent decades, the sections of the Southwest that were effectively colonized by Spain in the 16th to 19th centuries.

The cultural differences between these regional cultures have a greater effect on our politics than the size and density of our communities. I ran the numbers for the past three presidential elections, comparing the voting behaviors of rural and urban counties within each “nation.” In five regional cultures that together constitute about 51 percent of the United States population, rural and urban counties voted for the same presidential candidate, be it the “blue wave” election of 2008, the Trumpist upheaval of 2016 or the more ambiguous contest in between. In the Deep South, Greater Appalachia, New France and the Far West, rural and urban majorities supported Republican candidates in all three elections, whether voters lived in central cities, wealthy suburbs, mountain hollers or the ranches of the high plains. In El Norte, the Spanish-colonized parts of the Southwest, both types of counties — empty desert or booming cityscapes — voted Democratic.