Public libraries are funded through a wide combination of sources, the most significant which is usually local or municipal funding. The citizens who use a local library support it via the city or county government, or through a special-purpose district, which is a local government body that has independent leadership and may levy its own taxes. Local funding may be supplemented by other government funding. For example, in the United States, the state and federal governments provide supplementary funding for public libraries through state aid programs, the Library Services and Technology Act (LSTA) and E-Rate. State and local governments may also offer cities and counties large grants for library construction or renovation. Private philanthropy has also had a significant role in the expansion and transformation of library services, and, like other educational institutions, some libraries may be partially funded by an endowment. Some proactive librarians have devised alliances with patron and civic groups to supplement their financial situations. Library "friends" groups, activist boards, and well organized book sales also supplement government funding.