The Waltons are the richest family in America.

The descendants of Wal-Mart founder Sam Walton, the family controls more than 50% of the Wal-Mart Corporation, according to Bloomberg, and combined are worth at least $150 billion based on Forbes' wealth estimates.

Four Walton family members are currently in the top 10 on Forbes' list of the richest Americans. They have spent some of their money amassing huge collections of art, real estate, and expensive cars.

They also invest a portion of their fortune into charity, mainly through the Walton Family Foundation. But unlike some of today's millionaires who plan to donate most of their vast wealth to charity, the Waltons have used tax loopholes to keep getting richer.

Bloomberg's Zachary Mider recently wrote about how the Waltons have used estate tax loopholes to maintain their fortune. Specifically, they have done so by setting up so-called "Jackie O." trusts, which are ostensibly for charity, but can also be used to pass on money tax-free to heirs after a period of time.

Mider explains: "With a big enough spread between the actual performance and the IRS rate, a Jackie O. trust can theoretically save so much tax that it leaves a family richer than if it hadn’t given a dime to charity."

But despite the backlash, lawsuits, and the occasional scandal, Wal-Mart's first family isn't going anywhere — especially when 90% of Americans live within 15 miles of one of the gigantic chain's stores.