45 American families are worth more than $10 billion — and the wealthiest one is even richer than Elon Musk

• There are 45 American families with fortunes exceeding $10 billion, Forbes found.
• Walmart founder Sam Walton's heirs are richer than Elon Musk with a combined $267 billion fortune.
• The Mars, Marriott, Hearst, Koch, Lauder, Pritzker, and Rockefeller are all on the rich list.

There are 45 American families worth at least $10 billion, and the richest one is wealthier than Elon Musk.