As I have mentioned over the years, most recently here, environmental sustainability in all its forms is China’s toughest challenge (according to me). The Berkeley Earth group has produced an interactive real-time map of air pollution in China. It’s worth checking out. Right at this moment, as I post, it is showing good air quality in greater Beijing. That is unusual, and welcome. Please prowl around and check back.
America's worst problem is economic polarization and inequality. Our friends at the Geographical Information Systems company Esri, in cooperation with Amy Glasmeier of MIT, have produced a "living wage calculator" map, which shows the county-by-county difference between the minimum wage and the cost of living. This is also worth some careful study. Click on the “Explore the Map” button and you will see what I mean.