American Sunday-School Union

Founded in Philadelphia in 1817 as the Sunday and Adult School Union, the organization took the name American Sunday-School Union in 1824 as its work expanded beyond the city. It was created as a nondenominational effort to encourage Sunday schools and to supply them with libraries, lesson materials, and other practical support.

Over time, it became especially well known for its publishing program. The Union issued large numbers of moral and religious books, periodicals, and educational works, and later sources describe it as one of the most prolific publishers of children's books in 19th-century America. It also sent missionaries and organizers into underserved communities, including frontier regions, to establish new Sunday schools.

The organization did not remain static: later histories trace it forward through the names American Missionary Fellowship and then InFaith. For readers today, the American Sunday-School Union stands out both as a publisher and as a window into how religion, education, and children's literature were closely connected in the United States during the 1800s.