Perhaps the best place in the world to produce significant social impact is the United States. It is one of the richest countries in the world, and its cultural, economic, and political influence around the world is dominant.
In every area, social impact in America would be a giant step in the right direction for the entire world. For example, if Americans changed their attitudes towards energy, they could be the driving force of the next-stage in alternative energy, and in solving the climate crisis.
A more enlightened foreign policy would see American developing the global rule of law, enforcing human rights treaties, and making the world a safer place for the poor and the weak.
Enforcement of genuine American principles within the country -- non-discrimination, due process, freedom of speech and religious belief, and equality of opportunity -- would produce a society less divided, more tolerant, and with genuine economic access for all people regardless of their individual backgrounds like race, gender, color or creed.
It is this truth that can make the current state of affairs in America frustrating. It is frustrating because it takes just a little bit of thinking to see the great potential for human betterment that is potentially capable by American society. Instead, the country is divided more than ever, more economically unequal then ever, and appears charmed by "solutions" peddled by powerful interests that will cause more harm than good, and take the country backwards, and not forwards.
America is the country that put a person on the moon. It is not possible for America to get a free pass from stunning social achievements.
Want to have a significant social impact on the planet? Starting with America might be the best place to start.