The Public Broadcasting Service (PBS) is an American non-profit public broadcasting television service with 354 member TV stations in the United States which hold collective ownership. However, its operations are largely funded by the Corporation for Public Broadcasting. Its headquarters are in Arlington, Virginia. PBS is the most prominent provider of programming to U.S. public television stations, distributing series such as PBS NewsHour, Masterpiece, and Frontline. Since the mid-2000s, Roper polls commissioned by PBS have consistently placed the service as America's most trusted national institution. However, PBS is not responsible for all programming carried on public TV stations; in fact, stations usually receive a large portion of their content (including most pledge drive specials) from third-party sources, such as American Public Television, NETA, and independent producers.