”Agenda 21” was the theme of a 1992 United Nations conference on sustainable development. The agenda outlined various measures to address the challenges of poverty, health and other needs. It called for international cooperation to "support and supplement" national and local efforts, in line with usual U.N. efforts acknowledging the sovereignty of member governments. In 2015, the U.N. General Assembly adopted an updated "agenda" for 2030.
The ”Agenda 21” term has lived on in the U.S. among opponents of efforts to improve policy coordination across major metropolitan areas. Supporters of a 2013 lawsuit to block regional planning efforts in the San Francisco Bay Area claimed the U.N.'s Agenda 21 lay behind ideas to increase housing density and otherwise "take control" of private land use. The lawsuit was dismissed in 2019.