For the first time, Forbes magazine's list of the 400 richest Americans consists exclusively of people worth US$1 billion or more.
As a group, the people who made the rankings released on Thursday are worth a record US$1.25 trillion, compared to US$1.13 trillion last year.
In the billionaire-athon, casino magnate Sheldon Adelson pole-vaulted to No. 3 from 15th position in last year's ranking, finishing behind the mainstays at Nos. 1 and 2: Microsoft Corp founder Bill Gates and Warren Buffett of Berkshire Hathaway Inc.
Adelson is now estimated to have US$20.5 billion, Buffett US$46 billion and Gates US$53 billion. Gates has held the No. 1 spot for the last 13 years while Buffett has been No. 2 every year since 1994 except 2000, when Larry Ellison of Oracle Corp held that spot.
Adelson's expanding net worth is related in no small part to his decision to open a casino two years ago on the island of Macau, an emerging gambling haven off the southeastern coast of China.
Profits are growing rapidly thanks to the Las Vegas Sands Corp's Macau casino. Adelson personally and through family trusts controls 70 percent of the company, Las Vegas Sands spokesman Ron Reese said.
The two Google Inc founders were also big earners. Sergey Brin and Larry Page gained about US$13 million a day over the last two years, according to Forbes. That puts them in 12th and 13th place, up from a tie at 16th place last year.
Page and Brin also share the distinction of being, at 33 years old, the two youngest people on the list and two of only eight who are younger than 40.
The list was led off by technologists, such as Gates, Microsoft co-founder Paul Allen, Dell Inc's Michael Dell and Ellison.
Rounding it out are five members of the Walton family who have fortunes amassed from sales by the world's largest retailer, Wal-Mart Stores Inc.
Ellison, with US$19.5 billion, moved to fourth place from fifth, while Allen, last year's No. 3, was fifth this year with US$16 billion.
Dell fell to a tie at ninth place from fourth in last year's list; he is worth US$15.5 billion.
The biggest number of people on the list choose to live in California, which houses 90 of the 400, while another 44 have their homes on the other side of the US in New York City.