The most populous nations in the world are China, India, the United States, Indonesia, and Pakistan. However, China and India stand way out in front of the pack, with over a billion people each, while the U.S. has just over 325 million. Minute Earth looks into the reasons why. And even though the reasons are speculation, since China and India have always had more people than other countries, together they make perfect sense.
Think about it this way: the largest nations in the world by area have relatively few people: Russia and Canada (and Antarctica if it were a country). What do those nations have in common? You guessed it!