"Unmanned aircraft systems will be the most dynamic growth sector within aviation," the agency said in a report, which forecast that some 2.5 drones million will be in use by the end of 2016.
How the civilian drone market evolves, however, will depend on future security and regulatory measures put in place by the US government, the FAA said, emphasizing that "unprecedented milestones" were already set in 2015.
"This registration rule will aid in investigations and allow the FAA to gather data," the agency said in its report.
The number of hobby drones is expected to climb from 1.9 million in 2016 to 4.3 million in 2020, while commercial drones are predicted to soar from 600,000 to 2.7 million.
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However, the FAA added that predictions for commercial drones "are more difficult to develop given the dynamic, quickly-evolving nature of the market."
The agency worked with Teal Group, a drone industry expert, to better understand the market for unmanned aircraft systems.
An estimated 90 per cent of the drone fleet in 2020 will cost an average of USD 2,500. The most expensive models may reach USD 40,000.