Does the USA matter?

So much of this site (although started in the United States) is already about the USA, the Presidential election in 2008, the war in Iraq from an American perspective. Of the 6 billion people on the planet, though, the US has only 300 million. It did not even exist 300 years ago (as an entity). yet it has around 40% of wealth... But if I am the average person, being born in semi-rural India or China, living till 50 or 60, then dying...does the USA really have any impact on my life?