Microsoft founder and chairman Bill Gates has retained his top spot on the list of richest Americans for the twelfth year running.
The list published on Friday in Forbes Magazine showed that US President George W. Bush's policy of tax cuts has made America's wealthiest even wealthier with the top 400 now worth US$1.13 trillion -- up US$125 billion from last year's figure. It took US$900 million to make the top 400 list, compared with US$750 billion last year.
In total, the US now has 313 billionaires -- up from 262 last year. California alone boasts 98.
Gates led the list with US$51 billion, ahead of investor Warren Buffet with US$40 billion.
Gates' former partner Paul Allen was in third place with a net worth of US$22.5 billion, followed by computer mogul Michael Dell with US$18 billion. Software titan Larry Ellison, the founder of Oracle, came in fifth with a net worth of US$17 billion.
The remaining five members of the top 10 are members of the Walton family that is heir to the Wal-Mart fortune, each of whom is worth more than US$15 billion, Forbes estimated.
John Walton, who died in a plane crash in June, was replaced by his wife, Christy, at number six on the list, followed by Jim Walton, S. Robson Walton, Alice Walton and Helen Walton.
Steve Ballmer, the Microsoft chief executive, was ranked 11th with an estimated US$14 billion.
The top celebrity on the list was Star Wars creator George Lucas with US$3.5 billion, followed by tycoon-turned-reality TV star Donald Trump, and director Steven Spielberg with US$2.7 billion.
TV personas Oprah Winfrey and Martha Stewart also made the list, with US$1.4 billion and US$970 million respectively.
1. Bill Gates: US$51 billion
2. Warren Buffet: US$40 billion
3. Paul Allen: US$22.5 billion
4. Michael Dell: US$18 billion
5. Larry Ellison: US$17 billion
6. Christy Walton: US$15 billion
7. Jim Walton: US$15 billion
8. Robson Walton: US$15 billion
9. Alice Walton: US$15 billion
10. Helen Walton: US$15 billion
Source: Forbes Magazine
Google's co-founders Sergey Brin and Larry Page jumped to a tie for the number 16 spot as their fortunes more than doubled to US$11 billion each, Forbes said.
Among the notables who fell off the list this year was DreamWorks cofounder Jeffrey Katzenberg.
Forbes said Gates' financial strategy means that he "diversifies methodically, selling 20 million shares every quarter, reinvesting through Cascade Investment."
In addition to his Microsoft stock that makes up the vast majority of his wealth, he has "big stakes" in Canadian National Railway, Republic Services, and interestingly Berkshire Hathaway, which is controlled by Buffett.