Area 51 is the common name of a highly classified United States Air Force (USAF) facility within the Nevada Test and Training Range. A remote detachment administered by Edwards Air Force Base, the facility is officially called Homey Airport (XTA/KXTA) or Groom Lake. Details of its operations are not made public, but the USAF says that it is an open training range, and it is commonly thought to support the development and testing of experimental aircraft and weapons systems. The USAF acquired the site in 1955, primarily for flight testing the Lockheed U-2 aircraft.
California is a state in the Western United States. California borders Oregon to the north, Nevada and Arizona to the east, the Mexican state of Baja California to the south; and has a coastline along the Pacific Ocean to the west. With over 39.5 million residents across a total area of approximately 163,696 square miles (423,970 km2), it is the most populous and the third-largest U.S. state by area. It is also the most populated subnational entity in North America and the 34th most populous in the world. The Greater Los Angeles area and the San Francisco Bay Area are the nation's second and fifth most populous urban regions respectively, with the former having more than 18.7 million residents and the latter having over 9.6 million. Sacramento is the state's capital, while Los Angeles is the most populous city in the state and the second most populous city in the country. Los Angeles County is the country's most populous, while San Bernardino County is the largest county by area in the country. San Francisco, which is both a city and a county, is the second most densely populated major city in the country and the fifth most densely populated county in the country, behind four of New York City's five boroughs.
Houston is the most populous city in Texas, fourth-most populous city in the United States, most populous city in the Southern United States, as well as the sixth-most populous in North America, with a population of 2,304,580 in 2020. Located in Southeast Texas near Galveston Bay and the Gulf of Mexico, it is the seat and largest city of Harris County and the principal city of the Greater Houston metropolitan area, which is the fifth-most populous metropolitan statistical area in the United States and the second-most populous in Texas. Houston is the southeast anchor of the greater megaregion known as the Texas Triangle.
Tokyo, historically Tokio and officially the Tokyo Metropolis, is the capital and largest city of Japan. Its metropolitan area is the most populous in the world, with an estimated 37.468 million residents in 2018. Located at the head of Tokyo Bay, the prefecture forms part of the Kantō region on the central Pacific coast of Japan's main island of Honshu. Tokyo is the political and economic center of the country, as well as the seat of the Emperor of Japan and the national government. As of 2021, the prefecture has an estimated population of 14.04 million.
Dallas is a city in the U.S. state of Texas and the largest city in and seat of Dallas County, with portions extending into Collin, Denton, Kaufman and Rockwall counties. With a 2020 census population of 1,304,379, it is the ninth most-populous city in the U.S. and the third-largest in Texas after Houston and San Antonio. Located in North Texas, the city of Dallas is the main core of the largest metropolitan area in the Southern United States and the largest inland metropolitan area in the U.S. that lacks any navigable link to the sea. It is the most populous city in the Dallas–Fort Worth metroplex, the fourth-largest metropolitan area in the country at 7.5 million people.
A metropolitan area or metro is a region consisting of a densely populated Urban Agglomeration and its surrounding territories sharing industries, commercial areas, transport network, infrastructures and housing. A metro area usually comprises multiple principal cities, jurisdictions and municipalities: neighborhoods, townships, boroughs, cities, towns, exurbs, suburbs, counties, districts, and even states and nations like the eurodistricts. As social, economic and political institutions have changed, metropolitan areas have become key economic and political regions.
In the United States, a metropolitan statistical area (MSA) is a geographical region with a relatively high population density at its core and close economic ties throughout the area. Such regions are neither legally incorporated as a city or town would be, nor are they legal administrative divisions like counties or separate entities such as states; because of this, the precise definition of any given metropolitan area can vary with the source. The statistical criteria for a standard metropolitan area were defined in 1949 and redefined as metropolitan statistical area in 1983. A typical metropolitan area is centered on a single large city that wields substantial influence over the region. However, some metropolitan areas contain more than one large city with no single municipality holding a substantially dominant position. MSAs are defined by the U.S. Office of Management and Budget (OMB) and used by the Census Bureau and other federal government agencies for statistical purposes.
Population density is a measurement of population per unit area, or exceptionally unit volume; it is a quantity of type number density. It is frequently 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 square kilometre.
An unincorporated area is a region that is not governed by a local municipal corporation. Widespread unincorporated communities and areas are a distinguishing feature of the United States and Canada. Most other countries of the world have either no unincorporated areas at all, or these are very rare; typically remote, outlying, sparsely populated, or uninhabited areas.
A telephone numbering plan is a type of numbering scheme used in telecommunication to assign telephone numbers to subscriber telephones or other telephony endpoints. Telephone numbers are the addresses of participants in a telephone network, reachable by a system of destination code routing. Telephone numbering plans are defined in each of the administrative regions of the public switched telephone network (PSTN) and in private telephone networks.
An urban area, or built-up area, is a human settlement with a high population density and infrastructure of built environment. Urban areas are created through urbanization and are categorized by urban morphology as cities, towns, conurbations or suburbs. In urbanism, the term contrasts to rural areas such as villages and hamlets; in urban sociology or urban anthropology it contrasts with natural environment. The creation of early predecessors of urban areas during the urban revolution led to the creation of human civilization with modern urban planning, which along with other human activities such as exploitation of natural resources led to a human impact on the environment. "Agglomeration effects" are in the list of the main consequences of increased rates of firm creation since. This is due to conditions created by a greater level of industrial activity in a given region. However, a favorable environment for human capital development would also be generated simultaneously.
The Schengen Area is an area comprising 26 European countries that have officially abolished all passport and all other types of border control at their mutual borders. The area mostly functions as a single jurisdiction for international travel purposes, with a common visa policy. The area is named after the 1985 Schengen Agreement signed in Schengen, Luxembourg.
The San Francisco Bay Area, popularly referred to as the Bay Area, is a populous region surrounding the San Francisco, San Pablo, and Suisun Bay estuaries in Northern California. Although the exact boundaries of the region are variously defined, the Bay Area is defined by the Association of Bay Area Governments to include the nine counties that border the aforementioned estuaries: Alameda, Contra Costa, Marin, Napa, San Mateo, Santa Clara, Solano, Sonoma, and San Francisco. Other definitions may exclude parts of or even entire counties, or expand the boundaries to include neighboring counties that do not border the bay such as Santa Cruz and San Benito ; or San Joaquin, Merced, and Stanislaus.
