In the first half of the 19th century, many of the more affluent residents of New York’s Lower East Side neighborhood began to move further north, leaving their low-rise masonry row houses behind. At the same time, more and more immigrants began to flow into the city, many of them fleeing the Irish Potato Famine, or Great Hunger, in Ireland or revolution in Germany. Both of these groups of new arrivals concentrated themselves on the Lower East Side, moving into row houses that had been converted from single-family dwellings into multiple-apartment tenements, or into new tenement housing built specifically for that purpose.

A typical tenement building had five to seven stories and occupied nearly all of the lot upon which it was built (usually 25 feet wide and 100 feet long, according to existing city regulations). Many tenements began as single-family dwellings, and many older structures were converted into tenements by adding floors on top or by building more space in rear-yard areas. With less than a foot of space between buildings, little air and light could get in.

In many tenements, only the rooms on the street got any light, and the interior rooms had no ventilation (unless air shafts were built directly into the room). Later, speculators began building new tenements, often using cheap materials and construction shortcuts. Even new, this kind of housing was at best uncomfortable and at worst highly unsafe.

New York was not the only city in America where tenement housing emerged as a way to accommodate a growing population during the 1900s. In Chicago, for example, the Great Chicago Fire of 1871 led to restrictions on building wood-frame structures in the center of the city and encouraged the construction of lower-income dwellings on the city’s outskirts.

Unlike in New York, where tenements were highly concentrated in the poorest neighborhoods of the city, in Chicago they tended to cluster around centers of employment, such as stockyards and slaughterhouses. Nowhere, however, did the tenement situation become as dire as it was in New York, particularly on the Lower East Side. A cholera epidemic in 1849 took some 5,000 lives, many of them poor people living in overcrowded housing.

During the infamous New York draft riots that tore apart the city in 1863, rioters were not only protesting against the new military conscription policy; they were also reacting to the intolerable conditions in which many of them were living. The Tenement House Act of 1867 legally defined a tenement for the first time and set construction regulations; among these were the requirement of one toilet (or privy) per 20 people.

The existence of tenement legislation did not guarantee its enforcement, however, and conditions were little improved by 1889, when the Danish-born author and photographer Jacob Riis was researching the series of newspaper articles that would become his seminal book “How the Other Half Lives.”

Riis had experienced firsthand the hardship of immigrant life in New York City, and as a police reporter for newspapers, including The Evening Sun, he had gotten a unique view into the grimy, crime-infested world of the Lower East Side. Seeking to draw attention to the horrible conditions in which many urban Americans were living, Riis photographed what he saw in the tenements and used these vivid photos to accompany the text of “How the Other Half Lives,” published in 1890.

The hard facts included in Riis’ book–such as the fact that 12 adults slept in a room some 13 feet across, and that the infant death rate in the tenements was as high as 1 in 10–stunned many in America and around the world and led to a renewed call for reform.

Two major studies of tenements were completed in the 1890s, and in 1901 city officials passed the Tenement House Law, which effectively outlawed the construction of new tenements on 25-foot lots and mandated improved sanitary conditions, fire escapes and access to light. Under the new law–which in contrast to past legislation would actually be enforced–pre-existing tenement structures were updated, and more than 200,000 new apartments were built over the next 15 years, supervised by city authorities.

By the late 1920s, many tenements in Chicago had been demolished and replaced with large, privately subsidized apartment projects. The next decade saw the implementation of President Franklin D. Roosevelt’s New Deal, which would transform low-income housing in many American cities through programs including slum clearing and the building of public housing.

The first fully government-built public housing project opened in New York City in 1936. Called First Houses, it consisted of a number of rehabilitated pre-law tenements covering a partial block at Avenue A and East 3rd Street, an area that had been considered part of the Lower East Side.

Among the trendy restaurants, boutique hotels and bars that can be found in the neighborhood today, visitors can still get a glimpse into its past at the Lower East Side Tenement Museum, located at 97 Orchard Street.

Built in 1863, the building is an example of an “old-law” tenement (as defined by the Tenement House Act of 1867) and was home over the years for some 7,000 working class immigrants. Though the basement and the first floor have been renovated, the rest of the building looks much the same as it did in the 19th century, and has been designated a National Historic Site.