It must suck to be a wealth advisor in "North America's Siberia," home to two of the country's ten poorest counties. Unless you find a way to woo the 1 percent of the 1 percent away from Pacific Heights and the Upper East Side.

Enter Pierce H. McDowell III, president of South Dakota Trust Co. in Sioux Falls, and his "trust tsunami," a stay-rich-slowly scheme for the United States' tax-hating gazillionaires:

A branch of Chicago's Pritzker family rents space here, down the hall from the Minnesota clan that controls the Radisson hotel chain, and other rooms held by Miami and Hong Kong money.

Don't look for any heiresses in this former five-and-dime. Most days, the small offices that represent these families are shut. Even empty, they provide their owners with an important asset: a South Dakota address for their trust funds.

As Bloomberg's Zachary Mider reports, you don't even need to splurge on a stately prairie lodge to secure a legacy for your heirs—you just need a P.O. box in this largely unseen mole in the small of America's back. Most of America's huge financial families have done just that: Businesses in McDowell's building alone manage $89 billion worth of trusts, all told—for owners of TGI Friday's and Hyatt hotels, executives from Monster Beverage Co., and the Wrigley family, among others.

How'd this happen? You see, under the "ancient...Anglo-American" rules of primogeniture, dating back to an English court ruling in 1681, a wealthy noble could shelter some dough in a trust for his heirs, but only for the lifespan of his heirs, plus 21 years. Screw that socialist overregulation, said America's frontier jurists!

South Dakota repealed that rule in 1983, and unlike Idaho and Wisconsin — the other two states without the provision — it had no income tax. So, McDowell wrote, a trust set up here could shield a big fortune from taxes for centuries, escaping tax bills as it hands out cash to great-great-great-grandchildren and beyond.

The advantage of dynasty trusts is that they shield a family's wealth forever.

But the home of Mount Rushmore has plenty more to recommend itself to the monied—or, to their money, anyway:

The dynasty trust isn't South Dakota's only lure. Another attraction, for customers in places like New York and Massachusetts, is the chance to shelter their investments from income taxes in their home states…

Still others are drawn to South Dakota's iron-clad secrecy, and protections of trust assets from creditors and ex-wives.

What's a scheme like this do for society? As little as possible. It shelters billionaires' castles and investments from federal taxes in ways John Q. Public can't shelter his meager take-home paycheck. Even South Dakota doesn't see much tax revenue from all this financial activity. And the entire multi-billion-dollar system creates fewer jobs for South Dakotans than a single Walmart.

Don't worry, though: Walmart's founding family has a trust-based tax-avoidance scheme of its own. America: Showing British nobles how to really hang onto it since 1983!

[Photo credit: Holly Kuchera/Shutterstock]