We\’ve all probably seen that graph of population growth over the centuries, and the sudden spike in the 1800s. But when did the world get a realistic, mostly accurate count or estimate of all the people alive at the time. Had the 1 billion mark already been hit? Were people shocked at how high/low the number was?

Edit: I understand that censuses have been a thing for some time now. What I\’m asking is when was the WORLD population first known. That includes people in the New World as well as the Old, and everyone in between.

Edit 2: I don\’t literally mean an exact count of every individual human on the planet, since it\’s a bit unrealistic. Estimates are what I\’m looking for.