Betio is the largest township of Kiribati's capital city, South Tarawa, and the country's main port. The settlement is located on a separate islet at the extreme southwest of the atoll.Betio Post Office opened on 5 April 1957 and closed in 1964. Since the 1970s, the islet has become a major centre of economic activity in Kiribati, and a causeway to Bairiki was constructed in the early 1980s, leading to an increase in human contact with the island.