The Sisters of Charity of New York is a religious congregation of women in the Catholic Church whose primary missions are education and nursing and who are dedicated in particular to the service of the poor.  The founder of the order, Elizabeth Ann Seton, was canonized as the first American-born saint. As a widow, and in order to support her children, she taught school. Later she opened a Catholic school for girls  first in Baltimore and then in Emmitsburg she opened another Catholic school with  a small community of women who concentrated on a defined lifestyle for their religious congregation. They adopted the rule that Saints Vincent de Paul and Louise de Marillac had created in 17th century France.

Within a year, Elizabeth took vows and founded the first American congregation of women religious. In 1817 she sent three of her sisters to New York City to open an orphanage, establishing the foundation of the Sisters of Charity in New York.

From Wikipedia (links go to the Wikipedia article on that site):

The cholera epidemic of 1849 impelled the Sisters to open St. Vincent’s Hospital in Manhattan (closed 2010), the first Catholic hospital in New York City.⁵ St. Vincent’s Hospital became the centerpiece of an extensive health care system under the Sisters’ care that included St. Vincent’s Hospital in Westchester (a psychiatric hospital), as well as two hospitals on Staten Island: St. Vincent’s Hospital, Staten Island (closed 2006), and Bayley Seton Hospital, in addition to a network of nursing homes and other institutions.

The Sisters were also the key congregation in the establishment of New York’s parochial school system, staffing more schools than any other single order of women. In addition to parish schools (which, in New York, typically carry children through grade 8), the sisters ran a number of high schools themselves or provided staff for high schools run by others, and they established the College of Mount Saint Vincent, which also serves as their motherhouse.