If a solitary fact can stand in for Mr. Packer’s arguments in “The Unwinding,” it is probably this one, about the heirs to Walton’s Walmart fortune: “Eventually six of the surviving Waltons,” the author writes, “would have as much money as the bottom 30 percent of Americans.”

It was only after Walton’s death, Mr. Packer says, “that the country began to understand what his company had done.” He writes: “Over the years, America had become more like Walmart. It had gotten cheap. Prices were lower, and wages were lower. There were fewer union factory jobs, and more part-time jobs as store greeters.” He adds: “The hollowing out of the heartland was good for the company’s bottom line.”

“The Unwinding” contains many sweeping, wide-angle views of American life. Its portraits of Youngstown, Ohio; Tampa; Silicon Valley; Washington; and Wall Street are rich, complex and interlocking. Mr. Packer’s gifts are Steinbeckian in the best sense of that term.

Amid this narrative push are many small, memorable moments. The assessment of Mr. Biden is complicated and sometimes positive, but it includes these sentences, from one Biden insider to another: “Jeff, don’t take this personally. Biden disappoints everyone. He’s an equal-opportunity disappointer.”

Mr. Packer, whose previous books include “The Assassins’ Gate: America in Iraq” (2005), describes how Mr. Gingrich’s rhetoric, when he came to power in the late 1980s, forever changed the way elected leaders spoke to one another: “He gave them mustard gas, and they used it on every conceivable enemy, including him.”

He has a few complimentary things to say about Ms. Winfrey, but his section about her amounts to a comprehensive takedown. About her audience he maintains: “They had things that she didn’t — children, debts, spare time. They consumed the products that she advertised but would never buy — Maybelline, Jenny Craig, Little Caesars, Ikea. As their financial troubles grew, she would thrill them by selecting one of them and wiping out her debts on the air.”