The always fantastic Joel Kotkin lays out the argument:

Demographics

By 2030, all our major rivals, save India, will be declining, with ever-larger numbers of retirees and a shrinking labor force.  … By then, the U.S. will have 400 million people, which may be more than the entire EU and three times the population of our former archrival Russia.

Energy

In terms of energy resources, the U.S., combined with Canada, is the second richest region in the world after the Middle East. The country possesses vast resources of natural gas, about 90 years’ worth, as well as strong areas for wind power.

Food

America remains the world’s agricultural superpower, with the most arable land on the planet. With another 3 billion people expected on the planet by 2050, the U.S. should enjoy a continuing boom in food exports.

Military

The U.S. leads in military technology and, yes, our martial spirit remains a positive factor … Europe and Japan have taken themselves out of the military game, and it will be decades before China will be ready for a head-to-head challenge.

Innovation

There is no large country that comes close to the U.S. as an entrepreneurial hotbed (Taiwan, Israel and Hong Kong come close but are far smaller). The recent Legatum Prosperity Index showed the U.S. remains by far the largest generator of new ideas and companies on the planet.

Diversity

Over the past decade America has produced two African-American Secretaries of State and one President. America remains unique in its ability to absorb different races, religions and cultures, an increasingly critical factor in maintaining global preeminence.