United States National Radio Quiet Zone

The National Radio Quiet Zone (NRQZ) is a large area of land in the United States designated as a radio quiet zone, in which radio transmissions are heavily restricted by law to facilitate scientific research and the gathering of military intelligence. Roughly half of the zone is located in the Blue Ridge Mountains of west-central Virginia while the other half is the Allegheny Mountains of east-central West Virginia; a small part of the zone is in the southernmost tip of the Maryland panhandle.
Location.
The Quiet Zone is an approximate rectangle of land, on the north edge, on the south edge and on the east and west edges, comprising approximately . It straddles the borders of Virginia and West Virginia, and also includes a sliver of Maryland. The NRQZ is centered between the Green Bank Observatory in Green Bank, West Virginia, and Sugar Grove Station in Sugar Grove, West Virginia. It includes all land with latitudes between 37° 30′ 0.4″ N and 39° 15′ 0.4″ N, and longitudes between 78° 29′ 59.0″ W and 80° 29′ 59.2″ W.
Restrictions.
Most broadcast transmitters in the core of the Quiet Zone are forced to operate at reduced power and use highly directional antennas. This makes cable and satellite all but essential for acceptable television in much of the region. Restrictions on transmissions are tightest within ten miles (16 km) of the Green Bank and Sugar Grove facilities, where most omnidirectional and high-power transmissions are prohibited.
Not all radio transmissions are prohibited in the core of the Quiet Zone. For example, emergency service (police, fire, and ambulance) radios and CB radios are permitted. However, large transmitter owners must typically coordinate their operations with the Green Bank Observatory. The only broadcast radio stations are part of the Allegheny Mountain Radio network, with just one station in the AM band, and several low-power FM broadcast translator stations. Exceptions to restrictions are usually determined on a case-by-case basis, with preference given to public safety concerns, such as remote alarm systems, repeaters for emergency services, and NOAA Weather Radio.
The most severe restrictions imposed on the general public are only in place within the 20-mile (32 km) radius of the Green Bank Observatory. The Observatory actively polices the area for devices emitting noticeably high amounts of electromagnetic radiation such as microwave ovens, Wi-Fi routers and faulty electrical equipment and request citizens discontinue their usage. They possess no legal powers of enforcement (although the FCC can still impose a fine of $50 on violators), but will work with residents to find solutions.
Cellular telephone use in the core of the zone is also highly restricted. 
Zones of protection.
The Green Bank Interference Protection Group maintains policies to manage radio-frequency interference (RFI) by dividing into five zones based on available legal instruments.
Zone 1 and Zone 2 are located within the property of the Green Bank Observatory. The entire property is designed as Zone 1 except small portions (such as housing, visitor, and laboratory areas) that are designed as Zone 2. Zone 1, also called Radio Astronomy Instrument Zone, restricts intentional radiators to only those are deemed essential. All unintentional radiators must be operated within the recommendations on protection criteria used for radio astronomical measurements. Gasoline-powered motor vehicles are prohibited in Zone 1 as their spark-ignition engines generate significant radio interference, resulting in the requirement that all vehicles and equipment be diesel-powered. Zone 2, also called Observatory Building Zone, allows intentional radiators licensed by National Radio Quiet Zone, but not other radiators such as Wi-Fi, cordless phones, and other wireless equipment. Certain types of unintentional radiators are allowed, however digital cameras are prohibited, although film photography is allowed.
Zone 3 and Zone 4 are governed by the Radio Astronomy Zoning Act which is the Chapter 37A of the West Virginia Code. It strictly regulates radio transmitters within and within of the Green Bank Observatory, respectively. Within these zones, interference to observations will be identified and documented. The owners of the offending equipment will be personally visited to request cooperation in eliminating the interference. Enforcement is used as a last resort. Enforcement in Zone 4 may be more lenient than the limit set in the Chapter 37A.
Zone 5 is the boundary of National Radio Quiet Zone; the National Radio Quiet Zone Administrator at the Green Bank Observatory manages the enforcement policies.
Uses.
The Federal Communications Commission (FCC) created the Quiet Zone in 1958 to protect the radio telescopes at Green Bank and Sugar Grove from harmful interference. Today, the Green Bank Observatory oversees the Quiet Zone.
The Quiet Zone also protects the antennas and receivers of the U.S. Navy's Information Operations Command (NIOC) at Sugar Grove. The NIOC is the location of electronic intelligence-gathering systems, and is today said to be a key station in the ECHELON system operated by the National Security Agency (NSA).
The area has also attracted people who believe they suffer from electromagnetic hypersensitivity, though scientific experiments have shown this condition is caused by the nocebo effect rather than electromagnetic waves.
Cities inside the NRQZ.
West Virginia cities.
Clarksburg, West Virginia, and Lynchburg, Virginia, are just outside the Quiet Zone.