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World population - Wikipedia
Milestones by the billions
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World population milestones
World population milestones in billions (Worldometers estimates)
It is estimated that the world population reached one billion for the first time in 1804. It was another 123 years before it reached two billion in 1927, but it took only 33 years to reach three billion in 1960.
[66] Thereafter, the global population reached four billion in 1974, five billion in 1987, six billion in 1999 and, according to the United States Census Bureau, seven billion in March 2012.
[67] The United Nations, however, estimated that the world population reached seven billion in October 2011.
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According to current projections, the global population will reach eight billion by 2024, and is likely to reach around nine billion by 2042. Alternative scenarios for 2050 range from a low of 7.4 billion to a high of more than 10.6 billion.
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