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United Earth was a government organization in the Starfleet universe, responsible for the government of Earth and its colonies. It would later become one of the founding member states of the United Federation of Planets.
United Earth was an evolution of the United Nations of the 20th and 21st centuries. Following the first contact with the Vulcans in the mid 21st century, humanity finally began to put their differences aside and began fixing the problems that they had faced over the past couple hundred years. Humanity formed a unified planetary government in 2130s with the signing of the Traité d'Unification in Paris. The last holdouts - such as Australia - joined a few years later.
Soon after its founding United Earth formed a Starfleet which set out to explore local space, make contact with other governments, and establish Earth as an interstellar power. Due to the efforts of people such as Jonathan Archer, T'Pol, Trip Tucker the local species began making diplomatic progress for the first time in history, leading to the formation of the Coalition of Planets in 2154. The Romulan Star Empire fought a war against United Earth and her allies from 2156 through 2160.
One year after the end of the Earth-Romulan War United Earth became one of the five founding member states of the United Federation of Planets. United Earth's Starfleet became the backbone of the new Federation Starfleet. United Earth remained as a member government, representing and managing Earth and her major colonies throughout Federation history.
The Third Millennium
In the late 31st century a cataclysmic event called The Burn took place in which nearly all the galaxy's dilithium became inert and caused any ship with an active warp engine to explode, killing millions in the process. With interstellar travel becoming largely untenable and the Federation losing much of its power and influence, the Federation and Starfleet decided to move their respective headquarters off Earth following the Burn lest Earth become a target. After the Federation left Earth decided to secede from the Federation, with United Earth once again becoming a soverign nation in the process.
In Starfleet's absence the United Earth Defense Force was established and took over the planetary defense responsibilities. As Earth had a signifigant amount of dilithium this made the planet a target for pirates. In the years since the Federation left United Earth moved to make sure the planet was self-sufficient.