Cestus III Colony was the official name for the colony on planet Cestus III, admitted as a Federation member state in the year 2271. The colony had originally been established in 2265 as a Starfleet outpost, the Cestus III outpost, that was destroyed by the Gorn Hegemony in 2267. After diplomacy was established between the Federation and the Gorn, a treaty allowed the resettlement of the world by both parties.
The capital city of the Cestus III Colony was Pike City, and by the late 24th century the world had a population of 28 million Federation citizens and an additional 7 million Gorn settlers who shared the world peacefully. (ST reference: Star Charts)
The colony government was led by a democratically-elected governor. In 2379, Cestus Governor Nanietta Bacco launched a successful campaign for the office of President of the United Federation of Planets, following the unexpected resignation of her predecessor, President Min Zife. Bacco was succeeded as Governor of Cestus III by former Lieutenant Governor Yrolla Gari. (TNG - A Time to... novel: A Time for War, A Time for Peace; ST novel: Articles of the Federation)
Later that year, the colony was threatened by their star prematurely threatening to go supernova. The USS Enterprise-E was dispatched to evacuate the colony only for Cestus to return to normal before the evacuation. (TNG - The Q Conflict comic: "Issue 1")