South Carolina is a state in the coastal southeastern region of the United States. It is bordered to the north by North Carolina, to the southeast by the Atlantic Ocean, and to the southwest by Georgia across the Savannah River. South Carolina is the 40th most extensive and 23rd most populous U.S. state with a recorded population of 5,124,712 according to the 2020 census. In 2019, its GDP was $213.45 billion. South Carolina is composed of 46 counties. The capital is Columbia with a population of 133,273 in 2019; while its largest city is Charleston with a 2020 population of 150,277. The Greenville–Anderson–Mauldin metropolitan area is the largest in the state, with a 2018 population estimate of 906,626.South Carolina was named in honor of King Charles I of England, who first formed the English colony, with Carolus being Latin for "Charles". In 1712 the Province of South Carolina was formed. One of the Thirteen Colonies, South Carolina became a royal colony in 1719. During the American Revolution, South Carolina became part of the United States in 1776. South Carolina became the eighth state to ratify the U.S. Constitution on May 23, 1788. It was the first state to vote in favor of secession from the Union on December 20, 1860. After the American Civil War, it was readmitted into the United States on July 9, 1868. During the early to mid-20th century, the state started to see economic progress as many textile mills and factories were built across the state. South Carolina's economic diversification would continue into the early 21st century in industries such as aerospace, agribusiness, automotive manufacturing, and tourism.Within South Carolina from east to west are three main geographic regions, the Atlantic coastal plain, the Piedmont, and the Blue Ridge Mountains in the northwestern corner of Upstate South Carolina. South Carolina has primarily a humid subtropical climate, with hot humid summers and mild winters. Areas in the Upstate have a subtropical highland climate. Along South Carolina's eastern coastal plain are many salt marshes and estuaries. South Carolina's southeastern Lowcountry contains portions of the Sea Islands, a chain of barrier islands along the Atlantic Ocean.