Civil War. The geography of the state is marked by the Green Mountains, which run north–south up the middle of the state, separating Lake Champlain and other valley terrain on the west from the Connecticut River valley that defines much of its eastern border. A majority of its terrain is forested with hardwoods and conifers, and a majority of its open land is devoted to agriculture. The state's climate is characterized by warm, humid summers and cold, snowy winters. Vermont's economic activity of $34 billion in 2018 ranked last on the list of U.S. states and territories by GDP but 34th in GDP per capita. In 2000, the state legislature was the first to recognize civil unions for same-sex couples. , the state ranked 14th on the American Human Development Index. Etymology Samuel de Champlain claimed the area around what is now Lake Champlain, giving the name Vert Mont (Green Mountain) to the region he found, on a 1647 map. Evidence suggests that this name came into use among English settlers, before it morphed to "Vermont", ca. 1760. In 1777, Thomas Young introduced the name in writing with a broadside "To the Inhabitants of Vermont, a Free and Independent State". History Native American Between 8500 and 7000 BCE, at the time of the Champlain Sea, Native Americans inhabited and hunted in present-day Vermont. During the Archaic period, from the 8th millennium BCE to 1000 BCE, Native Americans migrated year-round. During the Woodland period, from 1000 BCE to 1600 CE, they established villages and trade networks, and developed ceramic and bow and arrow technology. Their population in 1500 CE was estimated to be around 10,000 people. During colonial times, where encounters and settlement were initiated by French colonists, the territory was occupied mainly by an Abenaki tribe known as the Sokoki, or Missisquois. The eastern part of the state may have also been occupied by the Androscoggin and Pennacook peoples. To the west, the Missisquois competed with the Iroquoian Mohawk, based in the Mohawk valley but with a large territory, and the Algonquin Mohican peoples. Many of the tribes later formed the Wabanaki Confederacy during King Philip's War. The warfare by English colonists defeated and scattered most of the surviving Abenaki tribes. Colonial The first European to see Vermont is thought to have been French explorer Jacques Cartier in 1535. On July 30, 1609, French explorer Samuel de Champlain claimed this