The Jamestown settlement in the Colony of Virginia was the first permanent English settlement in the Americas. It was located on the east bank of the James River about 2.5 mi southwest of the center of modern Williamsburg. It was established by the Virginia Company of London as "James Fort" on May 4, 1607 O. S.. It followed several failed attempts, including the Lost Colony of Roanoke, established in 1585 on Roanoke Island. Jamestown served as the capital of the colony of Virginia for 83 years, from 1616 until 1699; the settlement was located within the country of Tsenacommacah, which belonged to the Powhatan Confederacy, in that of the Paspahegh tribe. The natives welcomed and provided crucial provisions and support for the colonists, who were not agriculturally inclined. Relations soured early on, leading to the total annihilation of the Paspahegh in warfare within three years. Mortality was high at Jamestown itself due to disease and starvation, with over 80 percent of the colonists perishing in 1609–10 in what became known as the "Starving Time".
The Virginia Company brought eight Polish and German colonists in 1608 in the Second Supply, some of whom built a small glass factory—although the Germans and a few others soon defected to the Powhatans with weapons and supplies from the settlement. The Second Supply brought the first two European women to the settlement. In 1619, the first documented Africans came to Jamestown—about 50 men and children aboard a Portuguese slave ship, captured in the West Indies and brought to the Jamestown region, they most worked in the tobacco fields as indentured servants. The modern conception of slavery in the United States was formalized in 1640 and was entrenched in Virginia by 1660; the London Company's second settlement in Bermuda claims to be the site of the oldest town in the English New World, as St. George's, Bermuda was established in 1612 as New London, whereas James Fort in Virginia was not converted into James Towne until 1619, further did not survive to the present day. In 1676, Jamestown was deliberately burned during Bacon's Rebellion, though it was rebuilt.
In 1699, the capital was relocated from Jamestown to what is today Williamsburg, after which Jamestown ceased to exist as a settlement, existing today only as an archaeological site. Today, Jamestown is one of three locations composing the Historic Triangle of Colonial Virginia, along with Williamsburg and Yorktown, with two primary heritage sites. Historic Jamestowne is the archaeological site on Jamestown Island and is a cooperative effort by Jamestown National Historic Site and Preservation Virginia. Jamestown Settlement, a living history interpretive site, is operated by the Jamestown Yorktown Foundation, a state agency of the Commonwealth of Virginia. Spain and France moved to establish a presence in the New World, while other European countries moved more slowly; the English did not attempt to found colonies until many decades after the explorations of John Cabot, early efforts were failures—most notably the Roanoke Colony which vanished about 1590. Late in 1606, English colonizers set sail with a charter from the London Company to establish a colony in the New World.
The fleet consisted of the ships Susan Constant and Godspeed, all under the leadership of Captain Christopher Newport. They made a long voyage of four months, including a stop in the Canary Islands and subsequently Puerto Rico, departed for the American mainland on April 10, 1607; the expedition made landfall on April 1607 at a place which they named Cape Henry. Under orders to select a more secure location, they set about exploring what is now Hampton Roads and an outlet to the Chesapeake Bay which they named the James River in honor of King James I of England. Captain Edward Maria Wingfield was elected president of the governing council on April 25, 1607. On May 14, he selected a piece of land on a large peninsula some 40 miles inland from the Atlantic Ocean as a prime location for a fortified settlement; the river channel was a defensible strategic point due to a curve in the river, it was close to the land, making it navigable and offering enough land for piers or wharves to be built in the future.
The most favorable fact about the location was that it was uninhabited because the leaders of the nearby indigenous nations considered the site too poor and remote for agriculture. The island was swampy and isolated, it offered limited space, was plagued by mosquitoes, afforded only brackish tidal river water unsuitable for drinking; the Jamestown settlers arrived in Virginia during a severe drought, according to a research study conducted by the Jamestown Archaeological Assessment team in the 1990s. The JAA analyzed information from a study conducted in 1985 by David Stahle and others, who obtained borings of 800 year-old baldcypress trees along the Nottoway and Blackwater rivers; the lifespan of these trees is up to 1,000 years and their rings offer a good indication of an area's annual amount of rainfall. The borings revealed that the worst drought in 700 years occurred between 1606 and 1612; this severe drought affected the Jamestown colonists and Powhatan tribe's ability to produce food and obtain a safe supply of water.
The settlers arrived too late in the year to get crops planted. Many in the group were either gentlemen unused to work or their manservants, both unaccustomed to the hard labor demanded by the harsh task of carving out a viable colony. One of these was Robert Hunt, a former vicar of Reculver, England who
A census is the procedure of systematically acquiring and recording information about the members of a given population. The term is used in connection with national population and housing censuses; the United Nations defines the essential features of population and housing censuses as "individual enumeration, universality within a defined territory and defined periodicity", recommends that population censuses be taken at least every 10 years. United Nations recommendations cover census topics to be collected, official definitions and other useful information to co-ordinate international practice; the word is of Latin origin: during the Roman Republic, the census was a list that kept track of all adult males fit for military service. The modern census is essential to international comparisons of any kind of statistics, censuses collect data on many attributes of a population, not just how many people there are. Censuses began as the only method of collecting national demographic data, are now part of a larger system of different surveys.
Although population estimates remain an important function of a census, including the geographic distribution of the population, statistics can be produced about combinations of attributes e.g. education by age and sex in different regions. Current administrative data systems allow for other approaches to enumeration with the same level of detail but raise concerns about privacy and the possibility of biasing estimates. A census can be contrasted with sampling in which information is obtained only from a subset of a population. Modern census data are used for research, business marketing, planning, as a baseline for designing sample surveys by providing a sampling frame such as an address register. Census counts are necessary to adjust samples to be representative of a population by weighting them as is common in opinion polling. Stratification requires knowledge of the relative sizes of different population strata which can be derived from census enumerations. In some countries, the census provides the official counts used to apportion the number of elected representatives to regions.
In many cases, a chosen random sample can provide more accurate information than attempts to get a population census. A census is construed as the opposite of a sample as its intent is to count everyone in a population rather than a fraction. However, population censuses rely on a sampling frame to count the population; this is the only way to be sure that everyone has been included as otherwise those not responding would not be followed up on and individuals could be missed. The fundamental premise of a census is that the population is not known and a new estimate is to be made by the analysis of primary data; the use of a sampling frame is counterintuitive as it suggests that the population size is known. However, a census is used to collect attribute data on the individuals in the nation; this process of sampling marks the difference between historical census, a house to house process or the product of an imperial decree, the modern statistical project. The sampling frame used by census is always an address register.
Thus it is not known how many people there are in each household. Depending on the mode of enumeration, a form is sent to the householder, an enumerator calls, or administrative records for the dwelling are accessed; as a preliminary to the dispatch of forms, census workers will check any address problems on the ground. While it may seem straightforward to use the postal service file for this purpose, this can be out of date and some dwellings may contain a number of independent households. A particular problem is what are termed'communal establishments' which category includes student residences, religious orders, homes for the elderly, people in prisons etc; as these are not enumerated by a single householder, they are treated differently and visited by special teams of census workers to ensure they are classified appropriately. Individuals are counted within households and information is collected about the household structure and the housing. For this reason international documents refer to censuses of housing.
The census response is made by a household, indicating details of individuals resident there. An important aspect of census enumerations is determining which individuals can be counted from which cannot be counted. Broadly, three definitions can be used: de facto residence; this is important to consider individuals who have temporary addresses. Every person should be identified uniquely as resident in one place but where they happen to be on Census Day, their de facto residence, may not be the best place to count them. Where an individual uses services may be more useful and this is at their usual, or de jure, residence. An individual may be represented at a permanent address a family home for students or long term migrants, it is necessary to have a precise definition of residence to decide whether visitors to a country should be included in the population count. This is becoming more important as students travel abroad for education for a period of several years. Other groups causing problems of enumeration are new born babies, people away on holiday, people moving home around census day, people without a fixed address.
People having second homes because of working in another part of the country or retaining a holiday cottage are dif
Virginia the Commonwealth of Virginia, is a state in the Southeastern and Mid-Atlantic regions of the United States located between the Atlantic Coast and the Appalachian Mountains. Virginia is nicknamed the "Old Dominion" due to its status as the first English colonial possession established in mainland North America and "Mother of Presidents" because eight U. S. presidents were born there, more than any other state. 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. The Commonwealth's estimated population as of 2018 is over 8.5 million. 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 New World English colony. Slave labor and the land acquired from displaced Native American tribes each played a significant role in the colony's early politics and plantation economy.
Virginia was one of the 13 Colonies in the American Revolution. In the American Civil War, Virginia's Secession Convention resolved to join the Confederacy, Virginia's First Wheeling Convention resolved to remain in the Union. Although the Commonwealth was under one-party rule for nearly a century following Reconstruction, both major national parties are competitive in modern Virginia; the Virginia General Assembly is the oldest continuous law-making body in the New World. The state government was ranked most effective by the Pew Center on the States in both 2005 and 2008, it is unique in how it treats cities and counties manages local roads, prohibits its governors from serving consecutive terms. Virginia's economy has many sectors: agriculture in the Shenandoah Valley. S. Department of Defense and Central Intelligence Agency. Virginia has a total area of 42,774.2 square miles, including 3,180.13 square miles of water, making it the 35th-largest state by area. Virginia is bordered by Maryland and Washington, D.
C. to the north and east. Virginia's boundary with Maryland and Washington, D. C. extends to the low-water mark of the south shore of the Potomac River. The southern border is defined as the 36° 30′ parallel north, though surveyor error led to deviations of as much as three arcminutes; the border with Tennessee was not settled until 1893, when their dispute was brought to the U. S. Supreme Court; the Chesapeake Bay separates the contiguous portion of the Commonwealth from the two-county peninsula of Virginia's Eastern Shore. The bay was formed from the drowned river valleys of the James River. Many of Virginia's rivers flow into the Chesapeake Bay, including the Potomac, Rappahannock and James, which create three peninsulas in the bay; the Tidewater is a coastal plain between the fall line. It includes major estuaries of Chesapeake Bay; the Piedmont is a series of sedimentary and igneous rock-based foothills east of the mountains which were formed in the Mesozoic era. The region, known for its heavy clay soil, includes the Southwest Mountains around Charlottesville.
The Blue Ridge Mountains are a physiographic province of the Appalachian Mountains with the highest points in the state, the tallest being Mount Rogers at 5,729 feet. The Ridge and Valley region includes the Great Appalachian Valley; the region includes Massanutten Mountain. The Cumberland Plateau and the Cumberland Mountains are in the southwest corner of Virginia, south of the Allegheny Plateau. In this region, rivers flow northwest, into the Ohio River basin; the Virginia Seismic Zone has not had a history of regular earthquake activity. Earthquakes are above 4.5 in magnitude, because Virginia is located away from the edges of the North American Plate. The largest earthquake, at an estimated 5.9 magnitude, was in 1897 near Blacksburg. A 5.8 magnitude earthquake struck central Virginia on August 2011, near Mineral. The earthquake was felt as far away as Toronto and Florida. 35 million years ago, a bolide impacted. The resulting Chesapeake Bay impact crater may explain what earthquakes and subsidence the region does experience.
Coal mining takes place in the three mountainous regions at 45 distinct coal beds near Mesozoic basins. Over 64 million tons of other non-fuel resources, such as slate, sand, or gravel, were mined in Virginia in 2018; the state's carbonate rock is filled with more than 4,000 caves, ten of which are open for tourism, including the popular Luray Caverns and Skyline Caverns. The climate of Virginia is humid subtropical and becomes warmer and more humid farther south and east. Seasonal extremes vary from average lows of 26 °F in January to average highs of 86 °F in July; the Atlantic Ocean has a strong effect on southeastern coastal areas of the state. Influenced by the Gulf Stream, coastal weather is subject to hurricanes, most pronouncedly near the mouth of Chesapeake Bay. In spite of its position adjacent to the Atlantic Ocean the coastal areas have a significant continental influence with quite large temperature differences between summ
The Delmarva Peninsula, or Delmarva, is a large peninsula on the East Coast of the United States, occupied by Delaware and parts of the Eastern Shores of Maryland and Virginia. The peninsula is 170 miles long. In width, it ranges from 70 miles near its center, to 12 miles at the isthmus on its northern edge, to less near its southern tip of Cape Charles, it is bordered by the Chesapeake Bay on the west, the Delaware River, Delaware Bay, the Atlantic Ocean on the east, the Elk River and its isthmus on the north. In older sources, the peninsula between Delaware Bay and Chesapeake Bay was referred to variously as the Delaware and Chesapeake Peninsula or the Chesapeake Peninsula; the toponym Delmarva is a clipped compound of Delaware and Virginia, which in turn was modeled after Delmar, a border town named after two of those states. While Delmar was founded and named in 1859, the earliest uses of the name Delmarva occurred several decades and appear to have been commercial; the northern isthmus of the peninsula is transected by Delaware Canal.
Several bridges cross the canal, the Chesapeake Bay Bridge and the Chesapeake Bay Bridge–Tunnel join the peninsula to mainland Maryland and Virginia, respectively. Another point of access is Lewes, reachable by the Cape May–Lewes Ferry from Cape May, New Jersey. Dover, Delaware's capital city, is the peninsula's largest city by population, but the main commercial area is Salisbury, near its center. Including all offshore islands, the total land area south of the Chesapeake and Delaware Canal is 5,454 sq mi. At the 2000 census the total population was 681,030, giving an average population density of 124.86 inhabitants per square mile. Cape Charles forms the southern tip of the peninsula in Virginia; the entire Delmarva Peninsula falls within the Atlantic Coastal Plain, a flat and sandy area with few or no hills. The fall line, found in the region southwest of Wilmington and just north of the northern edge of the Delmarva Peninsula, is a geographic borderland where the Piedmont region transitions into the coastal plain.
Its Atlantic Ocean coast is formed by the Virginia Barrier Islands in the south and the Fenwick Island barrier spit in the north. The culture on Delmarva is starkly different from the rest of the Mid-Atlantic region and is much like that of the Southern United States. Many Delmarva counties are much more conservative than the "mainland" counties of Delaware and Virginia. Delmarva is driven by commercial fishing. Most of the land is rural, there are only a few large population centers. Many dialect studies show that Delmarva residents have a variation of Southern American English, prevalent in rural areas; the border between Maryland and Delaware, which resulted from the 80-year-long Penn–Calvert Boundary Dispute, consists of the east-west Transpeninsular Line and the perpendicular north-south portion of the Mason–Dixon line extending north to just beyond its tangental intersection with the Twelve-Mile Circle which forms Delaware's border with Pennsylvania. The border between Maryland and Virginia on the peninsula follows the Pocomoke River from the Chesapeake to a series of straight surveyed lines connecting the Pocomoke to the Atlantic Ocean.
All three counties in Delaware—New Castle and Sussex—are located on the peninsula. Of the 23 counties in Maryland, nine are on the Eastern Shore: Kent, Queen Anne's, Caroline, Wicomico and Worcester, as well as a portion of Cecil County. Two Virginia counties are on the peninsula: Northampton; the following is a list of some of the notable towns on the peninsula. Chestertown, Maryland, is the home of Washington College. Centreville, Maryland, is the county seat of Queen Anne's County. Easton, Maryland, is the county seat of Talbot County. St. Michael's, Maryland, is a popular tourist destination. Dover, Delaware, is the Delaware state capital and the peninsula's largest city in terms of population. Lewes, Delaware, is the site of the first European colonization in Delaware, is nicknamed "the first town in the first state", is a port city for the Cape May–Lewes Ferry. Ocean City, Maryland, is a popular resort town. Crisfield, Maryland, is a notable source of seafood. Seaford, the "Nylon Capital of the World", is the largest city in Sussex County.
Salisbury, Maryland, is the county seat of Wicomico County, the second largest city in the peninsula and the lower peninsula's only urbanized area. It is known as the "Crossroads of Delmarva", it is home to the Salisbury–Ocean City–Wicomico Regional Airport, the only airport on the peninsula with scheduled commercial flights. Delmar, part of the Salisbury Urbanized Area, lies across the Maryland-Delaware border from its twin, Delaware, on the Transpeninsular Line. Chincoteague, Virginia, is noted for its wild ponies and its beaches, administered by the U. S. Fish & Wildlife Service through Chincoteague National Wildlife Refuge. Princess Anne, Maryland, is the county seat of Somerset County. Cambridge, Maryland, is a busy port on the Choptank River. Rehoboth Beach, Delaware, "the Nation's Summer Capital", has a sixteenfold increase in population from winter to
1910 United States Census
The Thirteenth United States Census, conducted by the Census Bureau on April 15, 1910, determined the resident population of the United States to be 92,228,496, an increase of 21.0 percent over the 76,212,168 persons enumerated during the 1900 Census. The 1910 Census switched from a portrait page orientation to a landscape orientation; the 1910 census collected the following information: Full documentation for the 1910 census, including census forms and enumerator instructions, is available from the Integrated Public Use Microdata Series. The column titles in the census form are as follows: LOCATION. Street, road, etc. House number. 1. Number of dwelling house in order of visitation. 2. Number of family in order of visitation. 3. NAME of each person whose place of abode on April 15, 1910, was in this family. Enter surname first the given name and middle initial, if any. Include every person living on April 15, 1910. Omit children born since April 15, 1910. RELATION. 4. Relationship of this person to the head of the family.
PERSONAL DESCRIPTION. 5. Sex. 6. Color or race. 7. Age at last birthday. 8. Whether single, widowed, or divorced. 9. Number of years of present marriage. 10. Mother of how many children: Number born. 11. Mother of how many children: Number now living. NATIVITY. Place of birth of each person and parents of each person enumerated. If born in the United States, give the state or territory. If of foreign birth, give the country. 12. Place of birth of this Person. 13. Place of birth of Father of this person. 14. Place of birth of Mother of this person. CITIZENSHIP. 15. Year of immigration to the United States. 16. Whether naturalized or alien. 17. Whether able to speak English. OCCUPATION. 18. Trade or profession of, or particular kind of work done by this person, as spinner, laborer, etc. 19. General nature of industry, business, or establishment in which this person works, as cotton mill, dry goods store, etc. 20. Whether as employer, employee, or work on own account. If an employee— 21. Whether out of work on April 15, 1910.
22. Number of weeks out of work during year 1909. EDUCATION. 23. Whether able to read. 24. Whether able to write. 25. Attended school any time since September 1, 1909. OWNERSHIP OF HOME. 26. Owned or rented. 27. Owned free or mortgaged. 28. Farm or house. 29. Number of farm schedule. 30. Whether a survivor of the Union or Confederate Army or Navy. 31. Whether blind. 32. Whether deaf and dumb. Special Notation In 1912 and 1959, New Mexico, Arizona and Hawaii would become the 47th, 48th, 49th and 50th states admitted to the Union; the 1910 population count for each of these areas was 327,301, 204,354, 64,356 and 191,909 respectively. On this basis, the ranking list above would be modified as follows: First 42 ranked states - positions unchanged New Mexico, Arizona, Hawaii, Wyoming and Alaska; the original census enumeration sheets were microfilmed by the Census Bureau in the 1940s. The microfilmed census is available in rolls from the National Records Administration. Several organizations host images of the microfilmed census online, along which digital indices.
Microdata from the 1910 census are available through the Integrated Public Use Microdata Series. Aggregate data for small areas, together with electronic boundary files, can be downloaded from the National Historical Geographic Information System. 1911 U. S Census Report Contains 1910 Census results Historic US Census data census.gov/population/www/censusdata/PopulationofStatesandCountiesoftheUnitedStates1790-1990.pdf
Population density is a measurement of population per unit area or unit volume. It is applied to living organisms, most of the time to humans, it is a key geographical term. In simple terms population density refers to the number of people living in an area per kilometer square. Population density is population divided by total land water volume, as appropriate. Low densities may lead to further reduced fertility; this is called the Allee effect after the scientist. Examples of the causes in low population densities include: Increased problems with locating sexual mates Increased inbreeding For humans, population density is the number of people per unit of area quoted per square kilometer or square mile; this may be calculated for a county, country, another territory or the entire world. The world's population is around 7,500,000,000 and Earth's total area is 510,000,000 square kilometers. Therefore, the worldwide human population density is around 7,500,000,000 ÷ 510,000,000 = 14.7 per km2. If only the Earth's land area of 150,000,000 km2 is taken into account human population density is 50 per km2.
This includes all continental and island land area, including Antarctica. If Antarctica is excluded population density rises to over 55 people per km2. However, over half of the Earth's land mass consists of areas inhospitable to human habitation, such as deserts and high mountains, population tends to cluster around seaports and fresh-water sources. Thus, this number by itself does not give any helpful measurement of human population density. Several of the most densely populated territories in the world are city-states and dependencies; these territories have a small area and a high urbanization level, with an economically specialized city population drawing on rural resources outside the area, illustrating the difference between high population density and overpopulation The potential to maintain the agricultural aspects of deserts is limited as there is not enough precipitation to support a sustainable land. The population in these areas are low. Therefore, cities in the Middle East, such as Dubai, have been increasing in population and infrastructure growth at a fast pace.
Cities with high population densities are, by some, considered to be overpopulated, though this will depend on factors like quality of housing and infrastructure and access to resources. Most of the most densely populated cities are in Southeast Asia, though Cairo and Lagos in Africa fall into this category. City population and area are, however dependent on the definition of "urban area" used: densities are invariably higher for the central city area than when suburban settlements and the intervening rural areas are included, as in the areas of agglomeration or metropolitan area, the latter sometimes including neighboring cities. For instance, Milwaukee has a greater population density when just the inner city is measured, the surrounding suburbs excluded. In comparison, based on a world population of seven billion, the world's inhabitants, as a loose crowd taking up ten square feet per person, would occupy a space a little larger than Delaware's land area; the Gaza Strip has a population density of 5,046 pop/km.
Although arithmetic density is the most common way of measuring population density, several other methods have been developed to provide a more accurate measure of population density over a specific area. Arithmetic density: The total number of people / area of land Physiological density: The total population / area of arable land Agricultural density: The total rural population / area of arable land Residential density: The number of people living in an urban area / area of residential land Urban density: The number of people inhabiting an urban area / total area of urban land Ecological optimum: The density of population that can be supported by the natural resources Demography Human geography Idealized population Optimum population Population genetics Population health Population momentum Population pyramid Rural transport problem Small population size Distance sampling List of population concern organizations List of countries by population density List of cities by population density List of city districts by population density List of English districts by population density List of European cities proper by population density List of United States cities by population density List of islands by population density List of U.
S. states by population density List of Australian suburbs by population density Selected Current and Historic City, Ward & Neighborhood Density Duncan Smith / UCL Centre for Advanced Spatial Analysis. "World Population Density". Exploratory map shows data from the Global Human Settlement Layer produced by the European Commission JRC and the CIESIN Columbia University
Time in the United States
Time in the United States, by law, is divided into nine standard time zones covering the states and its possessions, with most of the United States observing daylight saving time for the spring and fall months. The time zone boundaries and DST observance are regulated by the Department of Transportation. Official and precise timekeeping services are provided by two federal agencies: the National Institute of Standards and Technology; the clocks run by these services are kept synchronized with each other as well as with those of other international timekeeping organizations. It is the combination of the time zone and daylight saving rules, along with the timekeeping services, which determines the legal civil time for any U. S. location at any moment. Before the adoption of four standard time zones for the continental United States, many towns and cities set their clocks to noon when the sun passed their local meridian, pre-corrected for the equation of time on the date of observation, to form local mean solar time.
Noon occurred at different times but time differences between distant locations were noticeable prior to the 19th century because of long travel times and the lack of long-distance instant communications prior to the development of the telegraph. The use of local solar time became awkward as railways and telecommunications improved. American railroads maintained many different time zones during the late 1800s; each train station set its own clock making it difficult to coordinate train schedules and confusing passengers. Time calculation became a serious problem for people traveling by train, according to the Library of Congress; every city in the United States used a different time standard so there were more than 300 local sun times to choose from. Time zones were therefore a compromise, relaxing the complex geographic dependence while still allowing local time to be approximate with mean solar time. Railroad managers tried to address the problem by establishing 100 railroad time zones, but this was only a partial solution to the problem.
Weather service chief Cleveland Abbe had needed to introduce four standard time zones for his weather stations, an idea which he offered to the railroads. Operators of the new railroad lines needed a new time plan that would offer a uniform train schedule for departures and arrivals. Four standard time zones for the continental United States were introduced at noon on November 18, 1883, when the telegraph lines transmitted time signals to all major cities. In October 1884, the International Meridian Conference at Washington DC adopted a proposal which stated that the prime meridian for longitude and timekeeping should be one that passes through the centre of the transit instrument at the Greenwich Observatory in the United Kingdom; the conference therefore established the Greenwich Meridian as the prime meridian and Greenwich Mean Time as the world's time standard. The US time-zone system grew from this, in which all zones referred back to GMT on the prime meridian. In 1960, the International Radio Consultative Committee formalized the concept of Coordinated Universal Time, which became the new international civil time standard.
UTC is, within about 1 second, mean solar time at 0°. UTC does not observe daylight saving time. For most purposes, UTC is considered interchangeable with GMT, but GMT is no longer defined by the scientific community. UTC is one of several related successors to GMT. Standard time zones in the United States are defined at the federal level by law 15 USC §260; the federal law establishes the transition dates and times at which daylight saving time occurs, if observed. It is the authority of the Secretary of Transportation, in coordination with the states, to determine which regions will observe which of the standard time zones and if they will observe daylight saving time; as of August 9, 2007, the standard time zones are defined in terms of hourly offsets from UTC. Prior to this they were based upon the mean solar time at several meridians 15° apart west of Greenwich. Only the full-time zone names listed below are official. View the standard time zone boundaries here; the United States uses nine standard time zones.
As defined by US law they are: From east to west, the four time zones of the contiguous United States are: Eastern Time Zone, which comprises the states on the Atlantic coast and the eastern two thirds of the Ohio Valley. Central Time Zone, which comprises the Gulf Coast, Mississippi Valley, most of the Great Plains. Mountain Time Zone, which comprises the states and portions of states that include the Rocky Mountains and the western quarter of the Great Plains. Pacific Time Zone, which comprises the states on the Pacific coast, plus Nevada and the Idaho panhandle. Alaska Time Zone, which comprises most of the state of Alaska. Hawaii-Aleutian Time Zone, which includes Hawaii and most of the length of the Aleutian Islands chain. Samoa Time Zone, which comprises American Samoa. Chamorro Time Zone, which comprises Guam and the Northern Mariana Islands. Atlantic Time Zone, which comprises Puerto Rico and the US Virgin Islands; some United States Minor Outlying Islands are outside the time zones defined by 15 U.
S. C. § exist in waters defined by Nautical time. In practice, military crews may