The group of tycoons as a whole are worth $1.25 trillion, compared with $1.13 trillion a year ago, Forbes magazine said.
Sheldon Adelson's incredible fortune comes mainly from his decision to open a casino in Macau, an island off south-eastern China famous for its gambling and Forbes estimate he has been making about $1m an hour for the past two years.
Two other top earners were the founders of the search engine giant Google and Apple Computers chief executive Steve Jobs was 49th on the list, with $4.9bn.
California is where 90 of the 400 on the list are living and another 44 have New York homes.
