U.S has had the benefit of favorable geopolitics(a good read:http://www.stratfor.com/analysis/geopolitics-united-states-part-1-inevitable-empire http://www.stra

U.S has had the benefit of favorable geopolitics(a good read:http://www.stratfor.com/analysis/geopolitics-united-states-part-1-inevitable-empire http://www.stratfor.com/analysis/geopolitics-united-states-p...). A large living space and a fairly sturdy inland waterways.Historically, the pressure on natural resources has been mitigated by easier transport of goods and people(unlike India which doesn't have inland waterways). In last few decades U.S has also closed gates on immigrants for good. Though that has slowed down the process of ghettoization, eventually large swathes of U.S will convert into American-Hispanic and other similar sub-cultures. And then it's just "my tribe vs. your tribe". The U.S is at the beginning of the road, and in time when there is a greater pressure on resources, you are looking at yet another India within the next 100-150 years. Let's just hope that it doesn't happen too soon and that human social mechanics today is advanced enough to handle another great civilization falling into chaos due to clash of cultures. The good news is that this time we have the Internet.