Greater New York has about twice the population of any other American city, and is exceeded only by London among the cities of the world. This has come about almost wholly in the nineteenth century, during which time the city grew at a rate never equaled. In the colonial period New York ranked below Boston and Philadelphia. In 1790 there was a population of 33,131 ; in 1800, 60,515 ; 1810, 96,373 ; 1820, 123,706 ; 1830, 202,589 ; 1840, 312,710; 1850, 515,477; 1860, 805,658; 1870, 942,292; 1880, 1,206,299 ; 1890, 1,515,301; and in 1900 (after the creation of a Greater New York), 3,437,202, including 1,850,093 in the Borough of Manhattan, 200,507 in the Borough of the Bronx, 1,166,582 in the Borough of Brooklyn, 152,999 in the Borough of Queens, and 67,021 in the Borough of Richmond. 

The suburbs on the New Jersey shore of the Hudson (Jersey City, Hoboken, etc.) contain about 300,000 inhabitants. Beyond these immediate suburbs we come to a section of New Jersey embracing Elizabeth, the Oranges, Montclair, Morristown, Plainfield, and many other places which are mainly suburbs of New York, in addition to the two great manufacturing centers of Newark and Paterson, also the homes of great numbers of New York businessmen. These places have a total population of about half a million. On the northeast the cluster of towns largely inhabited by persons doing business in New York extends beyond the boundary line of Connecticut.

Among these may be mentioned New Rochelle, Rye, Port Chester, Greenwich, and Stamford. The total population embraced within a radius of 25 miles from the New York City Hall is not far from five millions. As the city grew, the population of New York naturally tended to centre about the lower end of Manhattan, the business district. Inconveniences, too, incident to transportation across the river have aided in confining the population within the narrow limits of Manhattan Island, where the density of population is greater than in any other city whatsoever. The distribution of the population in Brooklyn is more normal.

In 1900, 66.70 per cent. of the population of Manhattan and the Bronx lived in dwellings containing twenty-one or more persons, while in Brooklyn the corresponding percentage was only 25.70 per cent. In Chicago it was 16.63. The density per acre in the Borough of Manhattan was 129.2. The region of greatest density is the lower East Side, where in the Eighth Assembly District, covering 98 acres of area, there was in 1900 a population of 735.9 to the acre. In the densely populated section, tenement houses having an average height of five or six stories, inadequately lighted and ventilated, and otherwise lacking in sanitary facilities, are the rule. Several large model tenement houses have recently been built, notably those of the City and Suburban Homes Company.

The housing problem, therefore is one of the most difficult with which the city has to deal, and presents phases almost unknown in other large centers of population. A radical tenement house law, which went into effect in 1902, is effecting a great improvement. The problem of congestion is closely related to that arising from the presence in the city of large classes of mostly poor foreigners. The various foreign elements tend to form distinct colonies. In the Eighth District, above mentioned, 67.2 per cent. of the population in 1900 were foreign born, and the greater part of the remainder were children of foreign-born parents. In 1900 the foreign born numbered 1,270,080, or 37 per cent. of the total population of the city.

In Manhattan alone, 41.5 per cent. of the total population was foreign born. New York has been always a strikingly cosmopolitan city. During the middle of the nineteenth century there was a very heavy German and Irish immigration to the city, but before the end of the century the immigration of these nationalities had greatly declined, and there had begun a heavy immigration from the south and east of Europe. According to the census of 1900 the principal foreign countries represented in the immigration to New York City in order of prominence were Germany, Ireland, Italy, Russia, Bohemia, Hungary and Austria, Poland, England, Scotland, and Wales. Few of the many Scandinavian immigrants to the United States have settled in New York. 

The large immigration from Austria-Hungary, Russia, and Poland consists almost wholly of Jews. Nearly one-fourth of the population of Manhattan are Jews. A large population of New York immigrants represent a class of unskilled laborers. The German immigrants, however, have always contained a large class of skilled artisans, who have participated in the more advanced industrial life of the city, and have contributed greatly to its social and artistic life. A much larger percentage of the Irish have been unskilled laborers.

The Italians have come mainly from the poorer districts of southern Italy, and almost all are laborers. Most of the coarser labor of the metropolis is done by them. The Jewish immigrants, like the Italians, are extremely poor and mostly unskilled. The majority are employed in the manufacture of clothing; many, however, are small merchants. Both of these elements keep to themselves. It is in the parts of the city occupied by them that the density of population is greatest. The negro population in 1900 numbered 60,666, of whom nearly two thirds were born outside of New York State. Of the total population of the city, 1,705,705 were males and 1,731,497 females.