The most powerful print publication in America might just be The National Enquirer. It functioned as a dirty-tricks shop for Donald J. Trump in 2016, which would have been the stuff of farce — the ultimate tabloid backs the ultimate tabloid candidate — if it hadn’t accomplished its goal.

The Enquirer’s power was fueled by its covers. For the better part of the campaign season, Enquirer front pages blared sensational headlines about Mr. Trump’s rivals from eye-level racks at supermarket checkout lanes across America. This stroke-of-genius distribution apparatus was dreamed up by the man who made The Enquirer the nation’s biggest gossip rag: its previous owner, Generoso Pope Jr.

The Enquirer’s racks, under the current chief, David J. Pecker, were given over to the Trump campaign. This was a political gift even more valuable than the $150,000 that The Enquirer paid in a “catch-and-kill” deal with the former Playboy model Karen McDougal for her story of an affair with Mr. Trump.

Wondering what The Enquirer’s covers were worth to the Trump campaign, I called Regis Maher, a co-founder of Do It Outdoors, the national mobile and digital billboard company. He said a campaign with that level of national prominence would cost $2.5 million to $3 million a month.