Earth, Vulcan, Andoria and Tellar sign the Federation Charter in San Francisco.
The United Federation of Planets was founded in 2161, when Earth, Vulcan, Andoria and Tellar signed its charter. It grew out of the Coalition of Planets that those worlds had begun forming in 2155, after years of cooperation that Captain Jonathan Archer and the crew of Enterprise had helped bring about.
The threats of the period pushed the founding worlds together. In Enterprise, a Romulan plot to provoke war between the Andorians and Tellarites was defeated by the four worlds working together, and the Earth-Romulan War that followed from 2156 to 2160 drew them closer still.
The signing ceremony in San Francisco appears in the Enterprise series finale, These Are the Voyages, in which Archer is about to give a speech to the delegates. Enterprise NX-01 was decommissioned the same year. Among the figures closely tied to the road to the Federation were Archer, T'Pol, the Andorian Shran and the Vulcan Ambassador Soval, who moved from deep distrust of humans to supporting them.