New Delhi: Women are a small but mighty force on the 2013 Forbes 400 Richest Americans list. Among them are: CEOs, heiresses and philanthropists.According to Forbes, The wealthiest women in the U.S. have gotten even richer over the past year, because of rising real estate prices and growing stock prices. It says the combined net worth of the ten richest women on The Forbes 400 is $156.6 billion, up from $124.2 billion last year. Altogether there are 48 women on this year's Forbes 400 list of richest Americans, up from 45 last year. The wealthiest woman in America is of course, Christy Walton, who is also the world's richest woman, with a net worth at $35.4 billion. Walton inherited a stake in retailer Wal-Mart and a chunk of stock in solar firm First Solar when her husband, John Walton, died in a plane crash in 2005. Walton, age 59, has faced a number of difficulties in her life in addition to her husband's death. Her son –her only child — battled cancer when he was just three years old and she fought a case of pneumonia that nearly killed her, according to the Imagen Foundation.Surprisingly, most of the women inherited their fortunes; only seven of the 45 started their own businesses or cofounded them with their husbands.Here is the complete list: 20. Pauline MacMillan KeinathNet Worth: $3 billionSource of wealth: Cargill Inc.Age: 78Overall Rank: 132The heiress is one of seven billionaire relatives who hold a majority of food production company Cargill, the largest private company in the U.S.19. Tamara GustavsonNet Worth: $3 billionSource of wealth: Public StorageAge: 50Overall Rank: 132The daughter of Public Storage founder B. Wayne Hughes also owns a commercial real estate company, American Commercial Equities Management LLC, in Malibu, Calif. 18. Karen PritzkerNet Worth: $3.2 billionSource of wealth: HyattAge: 54Overall Rank: 125She is a granddaughter of A.N. Pritzker (d. 1986), who built industrial conglomerate Marmon and hotel chain Hyatt.17. Barbara Piasecka JohnsonNet Worth: $3.3 billionSource of wealth: Johnson and JohnsonAge: 75 Overall Rank: 120Piasecka Johnson is the widow of Johnson and Johnson heir John Seward Johnson, who died in 1983 and left her the bulk of his fortune, including 18 million shares of the consumer goods company.16. Lynn SchustermanNet Worth: $3.5 billionSource of wealth: Samson ResourcesAge: 73Overall Rank: 113Schusterman is the widow of Oklahoma wildcatter Charles Schusterman (d. 2000), who built Samson Resources from nothing.15. Gayle CookNet Worth: $3.7 billionSource of wealth: Cook IncorporatedAge: 78Overall Rank: 104The widow of William Cook inherited her husband's stake in medical device company Cook Incorporated after he died in April of 2011.14. Nancy Walton LaurieNet Worth: $3.9 billionSource of wealth: Wal-MartAge: 61Overall Rank: 100The Wal-Mart heiress received a large amount of the retailer's stock after her father, James "Bud" Walton--brother of the retail giant's famous founder Sam--died in 1995.13. Marilyn Carlson NelsonNet Worth: $4 billionSource of wealth: Carlson Inc.Age: 73Overall Rank: 92Jointly owns Carlson Inc.--with hotel (Radisson, Country Inns & Suites), restaurant (T.G.I. Friday's) and travel (Carlson Wagonlit Travel) divisions--with her sister, Barbara Carlson Gage, and chairs the board. Her father, Curt (d. 1999), founded the company in the 1930s.12. Barbara Carlson GageNet Worth: $4 billionSource of wealth: Carlson Inc.Age: 70Overall Rank: 92Jointly owns Carlson Inc.--with hotel (Radisson, Country Inns & Suites), restaurant (T.G.I. Friday's) and travel (Carlson Wagonlit Travel) divisions--with her sister, Marilyn Carlson Nelson, who chairs the board. Her father, Curt (d. 1999), founded the company in the 1930s.11. Ann Walton KroenkeNet Worth: $4.5 billionSource of wealth: Wal-MartAge: 63Overall Rank: 79Wal-Mart, the world's largest retailer, was founded by Kroenke's uncle, Sam Walton.10. Randa WilliamsNet Worth: $4.7 billionSource of wealth: Enterprise Products PartnersAge: 51Overall Rank: 72Williams is the eldest of four children of the late energy pipeline entrepreneur Dan Duncan, founder of Enterprise Products Partners.9. Milane FrantzNet Worth: $4.7 billionSource of wealth: Enterprise Products PartnersAge: 43Overall Rank: 72Frantz is one of four children who inherited the massive fortune of late energy pipeline entrepreneur Dan Duncan, founder of Enterprise Products Partners.8. Dannine AvaraNet Worth: $4.7 billionSource of wealth: Enterprise Products PartnersAge: 48Overall Rank: 72Avara is one of four children who inherited the massive fortune of late energy pipeline entrepreneur Dan Duncan, founder of Enterprise Products Partners.7. Blair Parry-OkedenNet Worth: $5.4 billionSource of wealth: Cox EnterprisesAge: 61Overall Rank: 61The granddaughter of Cox Enterprises founder James M. Cox (d. 1957) inherited a 25% stake in the media company in 2007. It has revenues of nearly $15 billion.6. Anne Cox ChambersNet Worth: $10.7 billionSource of wealth: Cox EnterprisesAge: 92Overall Rank: 32At age 92, Chambers continues to sit on the board of privately held Cox Enterprises, which owns cable company Cox Communications, the Cox Media Group of newspapers, TV and radio stations, the Manheim automobile auction and AutoTrader.com. Her father, James M. Cox (d.1957), founded the company in 1898.5. Laurene Powell JobsNet Worth: $11 billionSource of wealth: Apple, DisneyAge: 48Overall Rank: 28The widow of legendary Apple cofounder Steve Jobs inherited a fortune after Jobs died in October 2011 that makes her the wealthiest woman in Silicon Valley.4. Abigail JohnsonNet Worth: $11.8 billionSource of wealth: FidelityAge: 50Overall Rank: 27The current president of Fidelity Financial Services may someday step into the CEO role of the company, which was founded by her grandfather in 1946.3. Jacqueline MarsNet Worth: $17 billionSource of wealth: MarsAge: 72Overall Rank: 16Jacqueline and her siblings, John and Forrest Jr., own $33 billion (estimated sales) Mars, the world's largest candy company.2. Alice WaltonNet Worth: $26.3 billionSource of wealth: Wal-MartAge: 63Overall Rank: 8The heiress is the daughter of Wal-Mart founder Sam Walton and a noted philanthropist. Last year, she opened Crystal Bridges Museum of American Art in the town of Bentonville, Ark., where Wal-Mart is headquartered.1. Christy WaltonNet Worth: $27.9 billionSource of wealth: Wal-MartAge: 57Overall Rank: 6The richest woman in the world holds most of her wealth in Wal-Mart, the retailer founded by her father-in-law Sam Walton and his brother James in 1962.