Net worth: $28.2 billion
Source of wealth: Wal-Mart
Christy Walton's net worth reached new highs as Wal-Mart stock jumped in 2012. She remains the richest woman in the United States. Christy inherited her wealth when husband John Walton, a former Green Beret and Vietnam war medic, died in an airplane crash in 2005.
9 richest billionaires of 2013
Bill Gates reclaimed his title as the world's richest man, according to the Bloomberg Billionaire Index. See how the rest of the richest of the rich rank...