China's urbanization push helped modernize its economy and has been a key component of its boom during the past two decades. But although the migration of hundreds of millions of workers from rural China to skyscrapers in the country's cities has been good for economic growth, it may turn out to be a weakness for the country in the future.

What China needs now, given its looming demographic crisis, is more babies, and a country built around workers crammed together in dense cities isn't the best thing for birthrates. A more suburban environment, like that in the United States, may be what China needs if it's to stave off population collapse.

If you were an evil genius who wanted to crush China's birthrate, you would have done just about everything the country has done during the past 40 years. First, when the country was still largely rural, you'd implement a one-child policy. Almost overnight, you'd make rural communities unviable by restricting the ability of agricultural workers to have large families to help work the fields. Young workers would realize they had little choice but to move to cities for work, creating the demographic demand for urban migration, which was then assisted by the state in the form of economic development and infrastructure programs.