Thursday's sale came a day after the Rosebud sled from Citizen Kane went for a staggering $US14.75 million, making it one of the priciest props in movie history.
They were part of the Summer Entertainment Auction being held all week by Heritage Auctions.
Heritage says the overall take has made it the second-highest grossing entertainment auction ever, and there is still a day to go.
Yet to be up for bids are Macaulay Culkin's knit snow cap from Home Alone, a Kurt Russell revolver from Wyatt Earp, a pair of Hattori Hanzo prop swords from Kill Bill Vol. 1 and a first edition set of Harry Potter novels signed by JK Rowling.
The whip sold Thursday was used during the Holy Grail trials that Ford's character goes through at the climax of 1989's Indiana Jones and the Last Crusade.
Ford gave it to then-Prince Charles at the film's UK premiere.
It was given as a gift to Princess Diana, who gave it to the current owner, who was not identified. The buyer also was not identified.
"The bull whip is the iconic symbol of an iconic character of cinema history, Indiana Jones, and has been a highlight of this auction," Heritage executive vice-president Joe Maddalena said.
The $US525,000 price includes the "buyers premium" attached to all auction items for the house that sells it.
Heritage said the nearly $US15 million bid for the Rosebud sled puts it second only to the $US32.5 million that Judy Garland's ruby slippers from The Wizard of Oz fetched in December.
Neither of those buyers were identified either.
The sled was sold by longtime owner Joe Dante, director of films including Gremlins.
Rosebud is the last word spoken by the title character in director Orson Welles' 1941 film Citizen Kane, and the hunt for its meaning provides the film's plot.
Many critics have regarded it as the best film ever made.