Billionaires' wealth and power have grown sharply over the past few years. Although the US doesn't have any royal families, it certainly has family empires with enormous fortunes — and influence.There are the Hearst and Newhouse families, who built publishing powerhouses; Estée Lauder, the founder of the cosmetics giant that generated the Lauder family fortune; and the families who created their wealth with retail and hotel empires, such as the Waltons with Walmart and the Pritzkers with Hyatt Hotels.Below are the 40 richest families in the US, ranked by estimated net worth from lowest to highest.The rankings were determined using the most up-to-date estimated net worths available from Forbes, released on July 29.

40. The (Charles & Rupert) Johnson family

Charles Johnson (left) is a majority owner of the San Francisco Giants.

Mike Coppola/Getty Images for the New York Philharmonic

Net worth: $13.4 billionSource of wealth: Franklin Resources, San Francisco GiantsIn 1947, Rupert Johnson founded Franklin Resources, a mutual fund company. A decade later, when Charles B. Johnson, Rupert's son, was 24, he took over as CEO and remained with the company for 56 years. Charles' brother, Rupert Johnson Jr., joined the company in 1965 and still serves as its vice chairman and director today.Charles' children also serve in the company, with Jennifer Johnson becoming CEO in 2020 and Greg Johnson serving as executive chairman.Today, the Johnson family owns 42% of the company, which went public in 1971. Forbes estimated in January that the firm had $1.7 trillion in assets under management.