The richest of all by far was John Jacob Astor at ten million dollars. No one else had more than three million, according to Beach, and only fifteen were worth as much as a million dollars. Although Astor was a German immigrant, most of the list’s fifteen millionaire families bore names from New York City’s old Knickerbocker aristocracy, such as Lorillard, Schermerhorn, Stuyvesant, and Suydam, families that had dominated New York society for generations.

Beach must have engaged in a great deal of guesswork and gossip sifting in order to compile his list, for the Knickerbockers valued their privacy, and public sources of information were few and far between in the 1840s. So popular was Beach’s list that it ran through many editions in its first year, and he soon added short explanations of where the money had come from. Some of these explanations are less than flattering to their subjects, and many are hilarious. In one instance he wrote that the Swords family had been “eminent booksellers many years past,” but noted that “the best literary speculation one of them made was his intermarriage with a Lorillard.”

By the time of Beach’s last edition, in 1855, the number of New York millionaires had swelled to thirty. While the Knickerbockers were mostly richer than ever, their fortunes were already being overshadowed by such non-Knickerbockers as Cornelius Vanderbilt, who had started life as a Staten Island farm boy, and A. T. Stewart, an immigrant from Ireland who more or less invented the department store.

With the Civil War there was a great explosion in both the number and the size of New York fortunes, and the Knickerbockers were quickly swamped by this tide of new wealth. “They find themselves supplanted by upstart princes of Shoddy, vulgar and with unknown grandfathers,” Mark Twain, then a correspondent for a San Francisco newspaper, wrote in 1867. “Their incomes, which were something for the common herd to gape at and gossip about once, are mere livelihoods now. . . . They move into remote new streets up town, and talk feelingly of the crash which is to come when the props are knocked from under this flimsy edifice of prosperity.”

But the crash did not come. Rather, the Gilded Age, the dazzling heyday of the nouveau riche, was dawning. By the 1880s, Ward McAllister, the self-appointed social arbiter of New York and creator of the phrase “the Four Hundred,” was forthright about what now counted in New York society. “Our catalogue,” he wrote anonymously in a pamphlet entitled “The 400,” “has been prepared with much

McAllister’s Four Hundred actually numbered 554. (In all probability he coined the phrase first and then realized that there was a certain irreducible minimum of people to be included, any of whom he could leave off the list only at his peril.) They were a mixture of some older, still wealthy New York families from the previous era and a great many more whose fortunes were squeaky new but vast in extent. Today, they would all be considered very old money indeed. And like the old money they supplanted, they have in their turn been supplanted by the fortunes created in the American economy of the twentieth century.

The secret of the American dream for 150 years has been that American society is open-ended at the top. Nothing that could be called an aristocracy has ever arisen in this country, because our greatest fortunes have always been our newest ones.