Ohio ( /ɵˈhaɪ.oʊ/ (help·info)) is a Midwestern state of the United States.[17] The thirty-fourth largest state by area in the U.S.,[18] it is the seventh-most populous with nearly 11.5 million residents.[19] Ohio, whose name was derived from the Seneca word ohi:yo’, meaning "large creek,"[20][21][22][23][24] was formed primarily from the Ohio Territory and was admitted to the Union as the seventeenth state[25] (and the first under the Northwest Ordinance)[25] on March 1, 1803.[8] Ohio is known as the "Buckeye State" for its prevalence of Ohio Buckeye trees, and, as such, Ohioans are also known as "Buckeyes."[1] The government of Ohio is composed of the executive branch, led by the Governor; the legislative branch, which comprises the Ohio General Assembly; and the judicial branch, which is led by the Supreme Court. Currently, Ohio occupies 18 seats in the United States House of Representatives.[26] Ohio is known for its status as both a swing state[27] and a bellwether[27] in national elections. The population density of Ohio ranks ninth among all U.S. states.[28] Nonetheless, Ohio currently suffers from a negative net population migration,[29] and an increasing rate of unemployment.[30] Ohio's geographic location has proven to be an asset for economic growth and expansion. Because Ohio links the Northeast to the Midwest, much cargo and business traffic passes through its borders along its well-developed highways. Ohio has the nation's 10th largest highway network, and is within a one-day drive of 50% of North America's population and 70% of North America's manufacturing capacity.[31] To the North, Lake Erie gives Ohio 312 miles (502 km) of coastline,[32] which allows for numerous seaports. Ohio's southern border is defined by the Ohio River (with the border being at the 1793 low-water mark on the north side of the river), and much of the northern border is defined by Lake Erie. Ohio's neighbors are Pennsylvania to the east, Michigan to the northwest, Ontario Canada, to the north, Indiana to the west, Kentucky on the south, and West Virginia on the southeast. Ohio's borders were defined by metes and bounds in the Enabling Act of 1802 as follows: Note that Ohio is bounded by the Ohio River, but nearly all of the river itself belongs to Kentucky and West Virginia. In 1980, the U.S. Supreme Court held that, based on the wording of the cessation of territory by Virginia (which, at that time included what is now Kentucky and West Virginia), the boundary between Ohio and Kentucky (and by implication, West Virginia) is the northern low-water mark of the river as it existed in 1792.[33] Ohio has only that portion of the river between the river's 1792 low-water mark and the present high-water mark. The border with Michigan has also changed, as a result of the Toledo War, to angle slightly northeast to the north shore of the mouth of the Maumee River. Much of Ohio features glaciated plains, with an exceptionally flat area in the northwest being known as the Great Black Swamp. This glaciated region in the northwest and central state is bordered to the east and southeast first by a belt known as the glaciated Allegheny Plateau, and then by another belt known as the unglaciated Allegheny Plateau. Most of Ohio is of low relief, but the unglaciated Allegheny Plateau features rugged hills and forests. The rugged southeastern quadrant of Ohio, stretching in an outward bow-like arc along the Ohio River from the West Virginia Panhandle to the outskirts of Cincinnati, forms a distinct socio-economic unit. Geologically similar to parts of West Virginia and southwestern Pennsylvania, this area's coal mining legacy, dependence on small pockets of old manufacturing establishments, and distinctive regional dialect set this section off from the rest of the state and, unfortunately, create a limited opportunity to participate in the generally high economic standards of Ohio. In 1965 the United States Congress passed the Appalachian Regional Development Act, at attempt to "address the persistent poverty and growing economic despair of the Appalachian Region."[34] This act defines 29 Ohio counties as part of Appalachia.[35] While 1/3 of Ohio's land mass is part of the federally defined Appalachian region, only 12.8% of Ohioans live there (1.476 million people.)[36] Significant rivers within the state include the Cuyahoga River, Great Miami River, Maumee River, Muskingum River, and Scioto River. The rivers in the northern part of the state drain into the northern Atlantic Ocean via Lake Erie and the St. Lawrence River, and the rivers in the southern part of the state drain into the Gulf of Mexico via the Ohio and then the Mississippi. The worst weather disaster in Ohio history occurred along the Great Miami River in 1913. Known as the Great Dayton Flood, the entire Miami River watershed flooded, including the downtown business district of Dayton. As a result, the Miami Conservancy District was created as the first major flood plain engineering project in Ohio and the United States.[37] Grand Lake St. Marys in the west central part of the state was constructed as a supply of water for canals in the canal-building era of 1820–1850. For many years this body of water, over 20 square miles (52 km²), was the largest artificial lake in the world. It should be noted that Ohio's canal-building projects were not the economic fiasco that similar efforts were in other states. Some cities, such as Dayton, owe their industrial emergence to location on canals, and as late as 1910 interior canals carried much of the bulk freight of the state. The climate of Ohio is a humid continental climate (Koppen climate classification Dfa) throughout most of the state except in the extreme southern counties of Ohio's Bluegrass region section which are located on the northern periphery of the humid subtropical climate and Upland South region of the United States. Summers are typically hot and humid throughout the State, while winters generally range from cool to cold. Precipitation in Ohio is moderate year-round. Severe weather is not uncommon in the state, although there are typically fewer tornadoes in Ohio than in states located in the so-called Tornado Alley. Severe lake effect snowstorms are also not uncommon on the southeast shore of Lake Erie, which is located in an area designated as the Snowbelt. Although predominantly not in a subtropical climate, some warmer-climate flora and fauna does reach well into Ohio. For instance, a number of trees with more southern ranges, such as the blackjack oak, Quercus marilandica, are found at their northernmost in Ohio just north of the Ohio River. Also evidencing this climatic transition from a subtropical to continental climate, several plants such as the Southern magnolia (Magnolia grandiflora), Albizia julibrissin (mimosa), Crape Myrtle, and even the occasional Needle Palm are hardy landscape materials regularly used as street, yard, and garden plantings in the Bluegrass region of Ohio; but these same plants will simply not thrive in much of the rest of the State. This interesting change may be observed while traveling through Ohio on Interstate 75 from Cincinnati to Toledo; the observant traveler of this diverse state may even catch a glimpse of Cincinnati's common wall lizard, one of the few examples of permanent "subtropical" fauna in Ohio. The highest recorded temperature was 113 °F (45 °C), near Gallipolis on July 21, 1934.[38] The lowest recorded temperature was -39 °F (-39 °C), at Milligan on February 10, 1899.[39] Although few have registered as noticeable to the average citizen, More than 30 earthquakes occurred in Ohio between 2002 and 2007, and more than 200 quakes with a magnitude of 2.0 or higher have occurred since 1776.[40] The most substantial known earthquake in Ohio history was the Anna (Shelby County) earthquake,[41] which occurred on March 9, 1937. It was centered in western Ohio, and had a magnitude of 5.4, and was of intensity VIII.[42] Other significant earthquakes in Ohio include:[43] one of magnitude 4.8 near Lima on September 19, 1884;[44] one of magnitude 4.2 near Portsmouth on May 17, 1901;[45] and one of 5.0 in LeRoy Township in Lake County on January 31, 1986, which continued to trigger 13 aftershocks of magnitude 0.5 to 2.4 for two months.[46][47] The most recent earthquake in Ohio of any appreciable magnitude occurred on January 8, 2008, at 8:34:46 PM local time. It had a magnitude of 3.1, and its epicenter was under Lake Erie, northeast of Cleveland, approximately 9.7 km (6 mi) west of Mentor-on-the-Lake.[48] The Ohio Seismic Network (OhioSeis), a group of seismograph stations at several colleges, universities, and other institutions, and coordinated by the Division of Geological Survey of the Ohio Department of Natural Resources,[49] maintains an extensive catalog of Ohio earthquakes from 1776 to the present day, as well as earthquakes located in other states whose effects were felt in Ohio.[50] Columbus (home of Ohio State University, Franklin University, Capital University, and Ohio Dominican University) is the capital of Ohio, near the geographic center of the state. Other Ohio cities functioning as centers of United States metropolitan areas include: Note: The Cincinnati metropolitan area extends into Kentucky and Indiana, and the Youngstown metropolitan area extends into Pennsylvania. Ohio cities that function as centers of United States micropolitan areas include: Archeological evidence suggests that the Ohio Valley was inhabited by nomadic people as early as 13,000 BC.[53] These early nomads disappeared from Ohio by 1,000 BC, "but their material culture provided a base for those who followed them".[53] Between 1,000 and 800 BC, the sedentary Adena culture emerged. As Ohio historian George W. Knepper notes, this sophisticated culture was "so named because evidences of their culture were excavated in 1902 on the grounds of Adena, Thomas Worthington's estate located near Chillicothe".[54] The Adena were able to establish "semi-permanent" villages because they domesticated plants, which included squash, sunflowers, and perhaps corn. Cultivation of these in addition to hunting and gathering supported more settled, complex villages.[54] The most spectacular remnant of the Adena culture is the Great Serpent Mound, located in Adams County, Ohio.[54]