There are at least 63 active drone sites around the U.S, federal authorities have been forced to reveal following a landmark Freedom of Information lawsuit.
The unmanned planes – some of which may have been designed to kill terror suspects – are being launched from locations in 20 states.
Most of the active drones are deployed from military installations, enforcement agencies and border patrol teams, according to the Federal Aviation Authority.
Exposed: Location of sites where licences have been granted for the use of drones within the U.S. There are 63 active sites based in 20 states. Red flags show active sites and blue show those locations where licences have expired since 2006
But, astonishingly, 19 universities and colleges are also registered as owners of what are officially known as unmanned aerial vehicles.
It is thought that many of institutions, which include Cornell, the University of Colorado, Georgia Tech, and Eastern Gateway Community College, are developing drone technology.
There are also 21 mainstream manufactures, such as General Atomics, who are registered to use drones domestically.
As well as active locations, the FAA also revealed 16 sites where licences to use spy planes have expired and four where authorisations have been disapproved, such as Otter Tail County, Minnesota.
Unusual: The University of Connecticut - one of 19 educational institutions to own spy planes - is the drone site closest to New York City. The North East is the region with the highest concentration
Concentration: The Beltway around Washington DC has the highest concentration of urban and suburban drone sites, including the U.S. Marine Corp base as Quantico Station, Virginia
The authority revealed the information after a Freedom of Information Act lawsuit by Electronic Frontier Foundation.
Its website hosts an interactive map that allows the user to zoom in to the area around where they live to see if any sites are nearby.
However, the FAA is yet to reveal what kinds of drones might be based at any of these locations.
The agency says it will release this data later.
Most of the drones are likely to be small craft, such as the Draganflyer X8, which can carry a payload of only 2.2lb.
Police, border patrols and environmental agencies, such as the National Oceanic and Atmospheric Administration (NOAA), could use for them effectively.
While few would object to vast open areas being monitored for wildfires, there are fears of privacy violations if drones are used to spy over cities.
Florida: Mostly police and Sheriff departments are registered to use drones in the state
Watch out Canada! Border agents are registered to use drone in North Dakota, just a few hundred miles from Winnipeg, Manitoba
Remote: The University of Alaska's drones are the most distant from any major urban centres. They are, however, the closest to Russia
Hotspot: Texas has one of the highest number of drone sites
West Coast: There are comparatively few drone sites in California and Western states
Other drones – likely to be operated only by the armed forces – might include the MQ-9 Reaper and the MQ-1 Predator, which was used to kill American Al Qaeda boss Anwar al-Awlaki in Yemen last September.
The FAA released two lists of public and private entities that have applied for authorisations to fly drones domestically.
Certificates of Authorizations (COAs), issued to public entities like police departments, are active in 42 locations, expired in 16 and disapproved in four.
Special Airworthiness Certificates (SACs), issued to private drone manufacturers, are active in 21 locations and not active in 17.
Among the other unanswered questions, however, are is exactly how many drones each registered user owns.
Killer: Some of the drones owned by the military might be the MQ-9 Reaper, which has been used to target terrorists overseas
Watching you: Most of the drones are likely to be small craft, such as the Draganflyer X8, which can carry a payload of only 2.2lb. Police, border patrols and environmental agencies, such as the National Oceanic and Atmospheric Administration (NOAA), could use for them effectively
The FAA has confirmed that there were about 300 active COAs and that the agency has issued about 700-750 authorizations since the program began in 2006.
But this information does not reveal how many are owned, for example, by Miami Dade Police Department.
While the use of drones in the U.S. is little known, American operations overseas have been well documented.
As well as high-profile terrorists, campaigners claim hundreds of innocent civilians have been killed in the border regions of Pakistan, where they are most active.
U.S. Air Force
Mississippi Department of Marine Resources
Arlington Police Department
Mississippi State University
City of Herington, Kansas
New Mexico Tech
City of North Little Rock, AR
Police Department Ogden Police Department
DARPA (Defense Advanced Research Projects Agency)
DHS (Department of Homeland Security) / CBP (Customs and Border Protection)
Orange County Sheriff's Office
DHS (Department of Homeland Security) / Science and Technology
Polk County Sheriff's Office
DOE (Department of Energy) - Idaho National Laboratory
Seattle Police Dept
Department of Agriculture - Agricultural Research Service
Texas A&M University Corpus Christi
Department of the Interior - National Business Center/Aviation Management Directorate
Texas A&M University - TEES
Eastern Gateway Community College University of Alaska Fairbanks
Texas State University University of Colorado
FBI (Federal Bureau of Investigation) University of Connecticut
Gadsden Police Department
Georgia Tech Research Institute University of Florida
Kansas State University University of North Dakota
USMC (United States Marine Corps)
Mesa County Sheriff's Office
Miami-Dade Police Department
Utah State University
Middle Tennessee State University
Virginia Polytechnic Institute and State University
New Mexico State University Physical Sciences Laboratory (NMSU-PSL)
Washington State Department of Transportation
NASA (National Aeronautics and Space Administration)