The United States Conference of Catholic Bishops (USCCB) is an assembly of the hierarchy of the United States and the U.S. Virgin Islands who jointly exercise certain pastoral functions on behalf of the Christian faithful of the United States. The purpose of the Conference is to promote the greater good which the Church offers humankind, especially through forms and programs of the apostolate fittingly adapted to the circumstances of time and place. This purpose is drawn from the universal law of the Church and applies to the episcopal conferences which are established all over the world for the same purpose.
The bishops themselves constitute the membership of the Conference and are served by a staff of approximately 315 lay people, priests, deacons, and religious located at the Conference headquarters in Washington, DC. There is also a small Office of Film and Broadcasting in New York City and a branch office of Migration and Refugee Services in Miami. The Conference is organized as a corporation in the District of Columbia.
Its purposes under civil law are: "To unify, coordinate, encourage, promote and carry on Catholic activities in the United States; to organize and conduct religious, charitable and social welfare work at home and abroad; to aid in education; to care for immigrants; and generally to enter into and promote by education, publication and direction the objects of its being."
Please visit their website, as it contains a wealth of information.