The United States is home to 515 billionaires with a combined net worth of more than US$2 trillion - and many favor New York over other American cities, according to the inaugural Wealth-X and UBS Billionaire Census 2013.

The report, the first-ever global study of this ultra high net worth (UHNW) tier, also highlights other super rich hotspots in the United States. Ninety-six billionaires have a primary business address in New York; Los Angeles is home to 22 billionaires;Chicago has 21; San Francisco has 20; and there are 14 billionaires in Houston.

The report also shows that the United States accounts for 34 percent of the combined net worth of the world's billionaires. The average net worth of an American billionaire is US$4 billion, of which 25 percent are liquid assets.

In terms of wealth source, the Wealth-X and UBS Billionaire Census 2013 reveals that 68 percent of America's billionaires made their fortunes, 22 percent inherited their wealth while 10 percent inherited and grew their wealth.

The average age of America's billionaires is 67 years old, which is above the global average of 62. Eighty-eight percent of the country's billionaires are male. 

Eighty percent of America's billionaire population have at least a college degree, with Harvard, Stanford and University of Pennsylvania being the most popular higher education institutions.

Wealth-X President David Friedman commented: "It's not surprising that – since the United States leads in terms of the number of billionaires – New York, the global financial capital, is the top place where billionaires congregate." 

To download the Wealth-X and UBS Billionaire Census 2013, visit the report's microsite at www.billionairecensus.com