Texas has the third-largest population of billionaires in the United States, according to U.S. News & World Report. Top-ranking billionaires in the state range from tech mogul Michael Dell to a variety of successful investment bankers, according to real-time data from Forbes. Many of the Texan billionaires on the list earned their fortune in the oil business. Visit Business Insider's homepage for more stories. Everything is bigger in Texas — including big business.