Chelsea is a neighborhood on the West Side of the borough of Manhattan in New York City. The area's boundaries are roughly 14th Street to the south, the Hudson River and West Street to the west, and Sixth Avenue to the east, with its northern boundary variously described as near the upper 20s
or 34th Street, the next major crosstown street to the north. To the northwest of Chelsea is the neighborhood of Hell's Kitchen, as well as Hudson Yards; to the northeast are the Garment District and the remainder of Midtown South; to the east are NoMad and the Flatiron District; to the southwest is the Meatpacking District; and to the south and southeast are the West Village and the remainder of Greenwich Village. Chelsea is named after the Royal Hospital Chelsea in London, England.

Chelsea contains the Chelsea Historic District and its extension, which were designated by the New York City Landmarks Preservation Commission in 1970 and 1981 respectively. The district was added to the National Register of Historic Places in 1977, and expanded in 1982 to include contiguous blocks containing particularly significant examples of period architecture.

The neighborhood is primarily residential, with a mix of tenements, apartment blocks, city housing projects, townhouses, and renovated rowhouses, but its many retail businesses reflect the ethnic and social diversity of the population. The area has a large LGBTQ population. Chelsea is also known as one of the centers of the city's art world, with over 200 galleries in the neighborhood.  due to the area's gentrification, there is a widening income gap between the wealthy living in luxury buildings and the poor living in housing projects, who are, at times, across the street from each other.

Chelsea is a part of Manhattan Community District 4 and Manhattan Community District 5, and its primary ZIP Codes are 10001 and 10011. It is patrolled by the 10th Precinct of the New York City Police Department.

History

Early development

Chelsea takes its name from the estate and Georgian-style house of retired British Major Thomas Clarke, who obtained the property when he bought the farm of Jacob Somerindyck on August 16, 1750. The land was bounded by what would become 21st and 24th Streets, from the Hudson River to Eighth Avenue. Clarke chose the name "Chelsea" after the Royal Hospital Chelsea in London, England. Clarke passed the estate on to his daughter, Charity, who, with her husband Benjamin Moore, added land on the south of the estate, extending it to 19th Street. The house was the birthplace of their son, Clement Clarke Moore, who in turn inherited the property. Moore is generally credited with writing "A Visit From St. Nicholas" and was the author of the first Greek and Hebrew lexicons printed in the United States.

In 1827, Moore gave the land of his apple orchard to the Episcopal Diocese of New York for the General Theological Seminary, which built its brownstone Gothic, tree-shaded campus south of the manor house. Despite his objections to the Commissioner's Plan of 1811, which ran the new Ninth Avenue through the middle of his estate, Moore began the development of Chelsea with the help of James N. Wells, dividing it up into lots along Ninth Avenue and selling them to well-heeled New Yorkers. Covenants in the deeds of sale specified what could be built on the land – stables, manufacturing and commercial uses were forbidden – as well as architectural details of the buildings.

Industrialization and entertainment district
The new neighborhood thrived for three decades, with many single family homes and rowhouses, in the process expanding past the original boundaries of Clarke's estate, but an industrial zone also began to develop along the Hudson. In 1847 the Hudson River Railroad laid its freight tracks up a right-of-way between Tenth and Eleventh Avenues, separating Chelsea from the Hudson River waterfront. By the time of the Civil War, the area west of Ninth Avenue and below 20th Street was the location of numerous distilleries making turpentine and camphene, a lamp fuel. In addition, the huge Manhattan Gas Works complex, which converted bituminous coal into gas, was located at Ninth Avenue and 18th Street.

The industrialization of western Chelsea brought immigrant populations from many countries to work in the factories, including a large number of Irish immigrants, who dominated work on the Hudson River piers that lined the nearby waterfront and the truck terminals integrated with the freight railroad spur. As well as the piers, warehouses and factories, the industrial area west of Tenth Avenue also included lumberyards and breweries, and tenements built to house the workers. With the immigrant population came the political domination of the neighborhood by the Tammany Hall machine, as well as festering ethnic tensions: around 67 people died in a riot between Irish Catholics and Irish Protestants on July 12, 1871, which took place around 24th Street and Eighth Avenue. The social problems of the area's workers provoked John Lovejoy Elliot to form the Hudson Guild in 1897, one of the first settlement houses – private organizations designed to provide social services.

A theater district had formed in the area by 1869, and soon West 23rd Street was the center of American theater, led by Pike's Opera House (1868, demolished 1960), on the northwest corner of Eighth Avenue. Chelsea was a busy entertainment district between about 1875 and 1900. Sixth Avenue contained the Ladies' Mile shopping district; music publishers opened offices in Tin Pan Alley along 28th Street; and the Tenderloin red-light district occupied the northern section of Chelsea.

Early and mid-20th centuries

The neighborhood was an early center for the motion picture industry before World War I. Some of Mary Pickford's first pictures were made on the top floors of an armory building at 221 West 26th Street, while other studios were located on 23rd and 21st Streets.

To accommodate high freight and industrial demand, several railroads had built rail freight terminals on the Manhattan side of the Hudson River, and many freight terminals and warehouses were built in the western part of Chelsea by the late 19th century. The first of these was the Central Stores, constructed at 11th Avenue between 27th and 28th Streets in 1891. This was followed in 1900 by the Lehigh Valley Railroad's terminal between 26th and 27th Streets, as well as the Baltimore and Ohio Railroad's terminal immediately to the south, completed in the early 1910s. Freight operations on Manhattan's far west side were improved when the elevated West Side Freight Line and the West Side Elevated Highway were built in the 1930s, replacing a surface-level railroad and roadway. 

London Terrace was one of the world's largest apartment blocks when it opened in 1930, with a swimming pool, solarium, gymnasium, and doormen dressed as London bobbies. Other major housing complexes in the Chelsea area are Penn South, a 1962 cooperative housing development sponsored by the International Ladies Garment Workers' Union, and the New York City Housing Authority-built and -operated Fulton Houses and Chelsea-Elliot Houses. 

The 23-story Art Deco Walker Building, which spans the block between 17th and 18th Streets just off of Seventh Avenue, was built in the early 1930s. That structure was converted in 2012 to residential apartments on the top 16 floors, with Verizon retaining the lower seven floors. In the early 1940s, tons of uranium for the Manhattan Project were stored in the Baker & Williams Warehouse at 513-519 West 20th Street. The uranium was removed and a decontamination project at the site was completed during the early 1990s. By the mid-20th century, the western part of Chelsea had various types of light manufacturing businesses. According to the New York City Landmarks Preservation Commission, these ranged "from printing shops and box companies, to milk-bottling plants and electrical wire and cable manufacturers".

Late 20th century to present 
The industrial character of West Chelsea declined in the 1960s and 1970s, as industries started to relocate from Manhattan. In subsequent years, the area's redevelopment was concentrated around West Chelsea, and some of the old industrial structures were converted to nightclubs. These included Les Mouches (housed in a former Otis Elevator Company factory) and the Tunnel (housed in the Central Stores building on 11th Avenue). Many LGBTQ people started moving to Chelsea in the mid-1980s, and upscale restaurants and stores began opening in the neighborhood around the same time. By then, the neighborhood also contained some of New York City's "cutting-edge theaters and performance spaces" according to The New York Times. By the late 1990s, West Chelsea had also begun to attract visual-arts galleries that had relocated from SoHo.

On September 17, 2016, there was an explosion outside a building on 23rd Street, which injured 29 people; police located and removed a second, undetonated pressure cooker bomb on 27th Street. A suspect, Ahmad Khan Rahami, was captured two days later after a gunfight in Linden, New Jersey. 

By the late 2010s, the eastern part of Chelsea, which had once been largely industrial, had also attracted upscale residential development.

Demographics
For census purposes, the New York City government classifies Chelsea as part of a larger neighborhood tabulation area called Hudson Yards-Chelsea-Flat Iron-Union Square. Based on data from the 2010 United States Census, the population of Hudson Yards-Chelsea-Flat Iron-Union Square was 70,150, a change of 14,311 (20.4%) from the 55,