The main consensus of various studies is that the population of earth hit 1 billion people in the first half of the 19th century. Eastern Europe, China and Japan were the main centers at this time. London and Beijing both numbered over 1,000,000 people at this time. The 1835 Paris census numbered 1,000,000 people. Vienna was somewhere between 300,000 and 400,000. Berlin was around 400,000 in 1830. New York at this time was slightly over 200,000 and by far the largest in America.