The old rules said that only the top-20 from the previous year's rankings were eligible.
The U.S. Golf Association also announced that the purse will increase from $500,000 to $5 million for the 2001 edition, which will be played at Southern Hills Country Club in Tulsa, Oklahoma.
Also announced by the U.S. Golf Association on Friday was that the top-two money leaders from the Japan PGA and the PGA Tour Australia will receive exemptions for the U.S. Open if they are in the top-75 in the World Golf Rankings.