United Nations officially declared October 12, 1999, as the "Day of Six Billion".

The UN marking that global population reached 6 billion.

This symbolic milestone was designated by the United Nations Population Fund (UNFPA), with the birth of Adnan Mević in Sarajevo, Bosnia and Herzegovina, recognized as the 6 billionth person.

However, later analyses, such as the UN's 2024 World Population Prospects, suggest the 6 billion mark was likely reached earlier, around mid-1998.

The U.S. Census Bureau estimated it occurred around June 18 or 19, 1999.