All the humans on Earth would fit in 500 square miles
People have been moving from rural areas to urban centers ever since the Industrial Revolution. This is not necessarily bad; many would argue that it is better for the planet. Having humans limited to giant metropolis can free up space for nature to do its own thing.
You might think that putting over 7.5 million people in one place would be impossible, but it is not that far-fetched. According to National Geographic, if every single human stood shoulder-to-shoulder, they would take up only 500 square miles, the size of Los Angeles.