Donald J. Trump, reality television star and real estate mogul, is different in many ways from major political figures in our past. But there are striking similarities between Mr. Trump and George C. Wallace, the Deep South politician who ran for president each opportunity he got from 1964 through 1976. The connections between the two — their rhetoric and their ability to fire up crowds — give us a better sense of what Trumpism will mean once he is gone from the campaign stage. After all, political losers as well as winners can shape the future.

Mr. Trump started his business career with what he called a “small loan” of a million dollars from his father. Mr. Wallace, the son of a struggling South Alabama farmer, clawed his way to power with hard work and a political antenna always ahead of the next public opinion poll.

And despite his reputation as a belligerent speechmaker, the insecure Mr. Wallace privately sought to ingratiate himself with friends and foes alike. It’s hard to imagine the egotistic Mr. Trump beginning a call to a hostile newspaper editor by cheerfully explaining, as Mr. Wallace once did, “I just called up to kiss your ass some more.”

What both share is the demagogue’s instinctive ability to tap into the fear and anger that regularly erupts in American politics.

Mr. Wallace’s 1963 inaugural address as governor of Alabama (“Segregation now, segregation tomorrow, segregation forever!”) and his “Stand in the Schoolhouse Door” that same year seemed to limit his role to that of a strictly regional figure, part of Dixie’s long tradition of racist politicians. His presidential candidacy in 1964 and surprising strength in Democratic primaries in Wisconsin, Indiana and Maryland did little to change that national image. In April 1967, when Mr. Wallace told a Syracuse, N.Y., audience that he had decided to run for president as a third-party candidate, the television networks ignored his announcement, as did most of the major newspapers. ...