Northeast megalopolis

The Northeast megalopolis, also known as the Northeast Corridor, Acela Corridor, Boston–Washington corridor, BosWash, or BosNYWash, is the world's largest megalopolis by economic output and the most populous megalopolis exclusively within the United States, with slightly over 50 million residents as of 2022.

Located primarily on the Atlantic Coast in the Northeastern United States, the Northeast megalopolis extends from the northern suburbs of Boston to Washington, D.C., running roughly southwesterly along a section of U.S. Route 1, Interstate 95, and the Northeast Corridor train line. It is sometimes defined more broadly to include other urban regions, including the Richmond and Hampton Roads regions to the south; Portland, Maine, and Manchester, New Hampshire, to the north; and Harrisburg, Pennsylvania, to the west.

The region includes many of the nation's most populated metropolitan areas, including those of New York City, Philadelphia, and Baltimore. As of 2010, it contained more than 50 million people, about 17% of the U.S. population on less than 2% of the nation's land area, with a population density of about 1,000 people per square mile (390 people/km2), far more than the U.S. average of 80.5 per square mile (31 people/km2). At least one projection estimates the area will grow to 58.1 million people by 2025.

French geographer Jean Gottmann popularized the term "megalopolis" in his 1961 study of the region, Megalopolis: The Urbanized Northeastern Seaboard of the United States. Gottmann concluded that the region's cities, while discrete and independent, are uniquely tied to each other through the intermeshing of their suburban zones, taking on some characteristics of a single, massive city: a megalopolis, a term he co-opted from an ancient Greek town of the same name that named itself out of aspirations to become the largest Greek city.

Region
The Northeast megalopolis includes many of the financial and political centers of influence in the United States, including the national capital of Washington, D.C., and all or part of 12 states (from north to south): Maine, New Hampshire, Massachusetts, Rhode Island, Connecticut, New York, New Jersey, Pennsylvania, Delaware, Maryland, West Virginia, and Virginia. The region is linked by Interstate 95 and U.S. Route 1, which start in Miami and Key West, Florida, respectively, in the south, and terminate in Maine at the U.S.-Canadian border. It is also linked by the Northeast Corridor train line, the country's busiest passenger rail line, serving Amtrak and several commuter rail agencies.

As of 2019, the region is home to 52.3 million people, and its metropolitan statistical areas are contiguous from Washington, D.C., in the south to Boston in the north. The region is not uniformly populated between the terminal cities, and there are regions nominally within the corridor yet located away from the main transit lines that have been bypassed by urbanization, such as the Quiet Corner in Connecticut.

The region accounts for 20% of the U.S. gross domestic product. It is home to two of the world's largest stock exchanges, the New York Stock Exchange and Nasdaq, and the headquarters of the United Nations in New York City, and the executive, legislative, and judicial centers of the U.S. federal government, the White House, the U.S. Capitol, and the U.S. Supreme Court in Washington, D.C. The region also is home to the headquarters of most of the nation and some of the world's largest media organizations, including ABC, NBC, CBS, NPR, PBS, Fox, Comcast, The New York Times Company, USA Today, New York Post, The Wall Street Journal, Newsday, The Washington Post, and The Boston Globe.

The global headquarters of many major financial firms, including JPMorgan Chase, Citigroup, Goldman Sachs, Morgan Stanley, Fannie Mae, Freddie Mac, Capital One, The Vanguard Group, and Fidelity, are located in the region. Among the world's 500 largest companies, 54 are based in the Northeast megalopolis. Among the 500 largest U.S.-based companies, 162 are headquartered in the region. The region is the center of the global hedge fund industry, which is heavily based in New York City and the suburban Connecticut cities of Greenwich and Stamford.

The Northeast megalopolis is home to hundreds of colleges and universities, including several that rank among world's most elite universities, including Harvard and MIT, both in Cambridge, Massachusetts, Brown in Providence, Rhode Island, Yale in New Haven, Connecticut, Columbia in New York City, Princeton in Princeton, New Jersey, the University of Pennsylvania in Philadelphia, Johns Hopkins in Baltimore, and Georgetown in Washington, D.C.

Economy
Total GDP of Northeast megalopolis is $5.2 trillion of which around $2.2 trillion is New York metropolitan area. If Northeast megalopolis was a sovereign nation (2022), it would rank in terms of nominal GDP as the world's third largest economy, ahead of Japan ($4.231 trillion).

History
Due to its proximity to Europe, the Eastern coast of the United States was among the first regions of the continent to be widely settled by Europeans. Over time, the cities and towns founded on the East Coast had the advantage of age over most other parts of the U.S. However, it was the Northeast in particular that developed most rapidly, owing to a number of fortuitous circumstances.

While possessing neither particularly rich soil—one exception being New England's Connecticut River Valley—nor exceptional mineral wealth, the region still supports some agriculture and mining. The climate is temperate and not particularly prone to hurricanes or tropical storms, which increase further south. However, the most important factor was the "interpenetration of land and sea," which makes for exceptional harbors, such as those at the Chesapeake Bay, the Port of New York and New Jersey, Narragansett Bay in Providence, Rhode Island, and Boston Harbor. The coastline to the north is rockier and less sheltered, and to the South is smooth and does not feature as many bays and inlets that function as natural harbors. Also featured are navigable rivers that lead deeper into the heartlands, such as the Hudson, Delaware, and Connecticut rivers, which all support large populations and were necessary to early settlers for development. Therefore, while other parts of the country exceeded the region in raw resource value, they were not as easily accessible, and often, access to them necessarily had to pass through the Northeast first.

Modern history
The Northeast played a significant role in the foundation of the United States during the late colonial era and in the American Revolutionary War. Pre-revolutionary events like the Gaspee affair, the Boston Massacre, Boston Tea Party, and the First Continental Congress all occurred in the region. In 1775, the Battles of Lexington and Concord, the first major battle of the Revolution, occurred in Massachusetts a few miles away from Boston. Many of the most significant battles took place in the region, including the Battle of Bunker Hill, the Battle of Monmouth, the Battle of Trenton, the Battle of Princeton, as well as several significant military campaigns such as the Philadelphia Campaign, the New York and New Jersey Campaign, the Boston Campaign, and the Yorktown Campaign. The surrender of the British occurred in the south end of the megalopolis after the Siege of Yorktown in 1781. Other significant events that occurred during the Revolution at this time in the region include the Second Continental Congress, the creation of the Articles of Confederation, the signing of the Declaration of Independence, and the Constitutional Convention.

During the Civil War, while most of the region did not experience fighting, there were many significant battles in the southern end of the region, particularly in Virginia. Major battles such as the Battle of Gettysburg, the Battle of Antietam, the Battles of Bull Run, the Battle of Fredericksburg, the Battle of Chancellorsville, and the Battles of Petersburg all occurred in the region. Additionally, Richmond acted as the capital of the Confederacy.

By 1800, the region included the only three U.S. cities with populations of over 25,000: Philadelphia, New York City, and Baltimore. By 1850, New York City and Philadelphia alone had over 300,000 residents while Baltimore, Boston, Brooklyn (at that time a separate city from New York), Cincinnati, and New Orleans had over 100,000: five were within one 400-mile strip while the last two were each four hundred miles away from the next closest metropolis. The immense concentration of people in one relatively densely packed area gave that region considerable sway through population density over the rest of the nation, which was solidified in 1800 when Washington, D.C., only 38 miles southwest of Baltimore, was made the nation's capital. According to Gottmann, capital cities "will tend to create for and around the seats of power a certain kind of built environment, singularly endowed, for instance, with monumentality, stressing status and ritual, a trait that will increase with duration." The transportation and telecommunications infrastructure that the capital city mandated also spilled over into the rest of the strip.

Additionally, the proximity to Europe, as well as the prominence of Ellis Island as an immigrant processing center, made New York City and cities nearby a "landing wharf for European immigrants," who represented an ever replenished supply of diversity of thought and determined workers. By contrast, the other major source of trans-oceanic immigrants was China, which was farther from the U.S. West Coast than Europe was from the East, and whose ethnicity made them targets of racial discrimination, creating barriers to their seamless integration into American society. By 1950, the region held over one-fifth of the total U.S. population, with a density nearly 15 times that of the national average.

The region has been home to the richest city in the nation for over 200 years: Hartford, Connecticut held the title from the pre–Civil War industrial era until about 1929, and New York City has held it since. Loudoun and Fairfax County, Virginia are the wealthiest counties in the country, and Connecticut's Gold Coast has one of the highest population densities of families worth over $30 million USD.

Concept
The concept of megalopolises originated with Jean Gottmann, a French geographer who wrote Megalopolis, a book whose central theory was that the cities between Washington, D.C., and Boston together form a sort of cohesive, integrated "supercity." He took the term megalopolis from a small Greek town that was settled in the Classical Era with the hope it would "become the largest of the Greek cities". The city still exists today, but is largely a sleepy agricultural community. However, the dream of the city's founders, Gottmann argued, was being realized in the Northeastern U.S. in the 1960s with the ascent of the region to global political, academic, and economic prominence.

Gottmann defined two criteria for a group of cities to be a true megalopolis: "polynuclear structure" and "manifold concentration:" that is, the presence of multiple urban nuclei, which exist independently of each other yet are integrated in a special way relative to sites outside their area.

Twin cities, such as Minneapolis–Saint Paul in Minnesota would not be considered a megalopolitan area since both cities are fairly integrated, even though both cities have distinct city borders and large central business districts. Large communities on the outskirts of major cities, such as Silver Spring or Bethesda in Maryland outside of Washington, D.C., are clearly distinct areas with even their own downtowns. However, they are not in any way independent of their host city, being still considered suburbs that would almost certainly not have developed in the ways that they have without the presence of Washington.

On the other hand, while the major cities of the Northeast megalopolis all are distinct, independent cities, they are closely linked by transportation and telecommunications. Neil Gustafson showed in 1961 that the vast majority of phone calls originating in the region terminate elsewhere in the region, and it is only a minority that are routed to elsewhere in the United States or abroad. In 2010 automobiles carried 80% of Boston-Washington corridor travel; intercity buses 8–9%; Amtrak 6%; and airlines 5%. Business ventures unique to the region have sprung up that capitalize on the interconnectedness of the megalopolis, such as airline shuttle services that operate short flights between Boston and New York City and New York City and Washington, D.C. that leave every half-hour, Amtrak's Acela Express high-speed rail service from Washington to Boston, and the Chinatown bus lines, which offer economy transportation between the cities' Chinatowns and elsewhere. Other bus lines operating in the megalopolitan area owned by national or international corporations have also appeared, such as BoltBus and Megabus. These ventures indicate not only the dual "independent nuclei"/"interlinked system" nature of the megalopolis, but also a broad public understanding of and capitalization on the concept.

In 2007, Gottmann's "megalopolis" concept was largely supported by John Rennie Short, who authored an update to Gottmann's book, Liquid City: Megalopolis and the Contemporary Northeast. National Geographic Society released a map in 1994 of the region at the time of the American Revolutionary War and in present day, which borrowed Gottmann's book's title. U.S. Senator Claiborne Pell wrote a book, Megalopolis Unbound in 1966, which summarized and expanded on Gottman's original book to outline his vision for a cohesive transportation policy in the region, including his state of Rhode Island. In 1967, futurists Herman Kahn and Anthony Wiener coined the term "BosWash" to predict that the region would emerge as the sort of megalopolis initially described by Gottmann.