Three of the six members of the Walton family who occupy space on the Forbes 400 list of the richest Americans are in the top ten, and a fourth ranks at number 11. They have a collective worth of about $100 billion, and as of 2007, the family commanded more wealth than the entire bottom 30 percent of Americans. They use their disproportionate capital to exert a disproportionate influence over American politics.

The family’s wealth is the legacy of Walmart founder Sam Walton and his brother James, a co-founder. Just under 50 percent of the company’s publicly traded shares are still owned by the family company, Walton Enterprises. Although Sam Walton wasn’t particularly involved in politics, his children and those of his brother (plus one widowed daughter-in-law, Christy Walton, who currently ranks as the richest woman in the world) have become increasingly political since the late 1990s. They supported President George W. Bush, donating $2.6 million to Progress for America in support of his re-election. During Bush’s tenure, Walton Enterprises hired a lobbyist to push for a low-tax agenda that included the repeal of the estate tax. The 2012 election cycle’s contributions from Walton family members, according to the Center for Responsive Politics, “favor the right decisively.” They’ve given at least $400,000 to pro-Mitt Romney super PAC Restore our Future, and also supported a super PAC favoring Jon Huntsman.

Through the Walton Family Foundation, whose board of directors consists entirely of members of the family, the Waltons hand out a few hundred million dollars per year in charitable donations. In 2010, the foundation’s giving totaled nearly $1.5 billion, thanks largely to an $800 million grant to establish the Crystal Bridges art museum in Arkansas.

While the charities the foundation supports vary widely, of particular interest are environmental conservation and “school choice,” the semi-privatization of the public school system through vouchers and charter schools. In 2011, the foundation’s school choice grants exceeded $159 million, $58 million of which was spent on initiatives seeking to impact public policy. The top recipients were the Charter School Growth Fund, followed by Teach for America, to which the foundation has pledged nearly $50 million over the next five years.

The foundation has also donated generously to the conservative infrastructure. A top recipient over the years has been the Hoover Institution, receiving over $4 million. Over $1.5 million has gone to the Center for Policy Studies. Grover Norquist’s Americans for Tax Reform, the Manhattan Institute, and the climate science skeptics at the Heartland Institute have each gotten hundreds of thousands of dollars. The Cato Institute and the Heritage Foundation have received tens of thousands.