No. 7 Country With Highest Density of Millionaires: United States
Millionaire households as a share of country's total households: 4.5%
Number of millionaire households: 5,220,000
2009 ranking: 7
After declining in 2008, the U.S. millionaire population grew in 2009 and continued to rebound in 2010, according to BCG. While the economy has shown only slight improvement, the U.S. still has by far the most millionaire households of any country, as well as the largest number of ultra-high-net-worth households (those with more than $100 million in assets under management).