The US is the third most populous country on earth, with over 320 million people according the current U.S. Census Population Clock. Yet, only around 4.4% of the world’s people live in the country and considering it’s only the 180th most densely populated country on earth, it’s rather sparsely populated.
Moreover, if the US ever wanted to catch-up with China (most populated) or India (soon to be most populated), it would have to increase its population fourfold (1.2 billion+). Even then, this would still only make it the 89th most densely populated country on earth (assuming of course no population changes in any other country).
However, all this can be rather difficult to visualize. Wouldn’t it be easier to just see how the current US population fits into the rest of the world? Well the clever users of reddit have done just that. They’ve created all the maps on this page that help show how large (or not) America’s population really is.