Virginia, officially the Commonwealth of Virginia, is a state in the Mid-Atlantic and Southeastern regions of the United States, between the Atlantic Coast and the Appalachian Mountains. The geography and climate of the Commonwealth are shaped by the Blue Ridge Mountains and the Chesapeake Bay, which provide habitat for much of its flora and fauna. The capital of the Commonwealth is Richmond; Virginia Beach is the most-populous city, and Fairfax County is the most-populous political subdivision. The Commonwealth's population in 2020 was over 8.65 million, with 36% of them living in the Baltimore–Washington metropolitan area. The area's history begins with several indigenous groups, including the Powhatan. In 1607, the London Company established the Colony of Virginia as the first permanent English colony in the New World. Virginia's state nickname, the Old Dominion, is a reference to this status. Slave labor and land acquired from displaced native tribes fueled the growing plantation economy, but also fueled conflicts both inside and outside the colony. Virginia was one of the original Thirteen Colonies in the American Revolution, and battles in Virginia secured the independence of the United States. During the American Civil War, Virginia was split when the state government in Richmond joined the Confederacy, but many of the state's northwestern counties remained loyal to the Union, becoming the state of West Virginia in 1863. Although the Commonwealth was under one-party rule for nearly a century following the Reconstruction era, both major political parties are competitive in modern Virginia. Virginia's state legislature is the Virginia General Assembly, which was established in July 1619, making it the oldest current law-making body in North America. It is made up of a 40-member Senate and a 100-member House of Delegates. The state government is unique in how it treats cities and counties equally, manages local roads, and prohibits governors from serving consecutive terms. Virginia's economy has many sectors: agriculture in the Shenandoah Valley; high tech and federal agencies, including the headquarters of the U.S. Department of Defense and Central Intelligence Agency, in Northern Virginia; and military facilities in Hampton Roads, the site of the region's main seaport.