The 10 richest Americans Despite the stalled economy, America's richest continue to get richer. As a group, the wealthiest 400 are worth $1.5 trillion, roughly the GDP of Canada. By Luisa Kroll and Kerry A. Dolan, Forbes.com A good year at the top The 400 richest Americans saw their collective wealth grow by 12% over the past year, meaning the nation's wealthiest slightly outperformed the Standard & Poor's 500 Index ($INX) over the period. Bill Gates is the nation's richest person for the 18th consecutive year; the last time he didn't rank No. 1 was 1993, when his good friend Warren Buffett eclipsed him. Buffett's fortune tumbled by $6 billion this year, making him the biggest loser among the nation's most wealthy. Buffett gave away $3.3 billion, and he was pinched by a 10% decline in the value of Berkshire Hathaway (BRK.A) stock. This year's headlines may belong to a younger group of entrepreneurs marching their way up the ranks, particularly those ...