The Federal Aviation Administration (FAA) predicts that some seven million drones will fly in the US by 2020 - nearly triple the number expected in the country by the end of 2016.
"Unmanned aircraft systems will be the most dynamic growth sector within aviation," said the FAA, which forecast that around 2.5 million drones will be in US skies by year end.
Last December, the agency passed rules calling for registration of small unmanned aircraft weighing more than 250 grams (0.55 pounds) and less than 25 kilograms (55 pounds), including payloads such as onboard cameras.
"This registration rule will aid in investigations and allow the FAA to gather data," it noted.
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, AFP reported.
However, the FAA added that predictions for commercial drones "are more difficult to develop given the dynamic, quickly-evolving nature of the market."
The FAA will publish final regulations regarding drone use within the next few months, it said.
An estimated 90 percent of the drone fleet in 2020 will cost an average of $2,500. The most expensive models may reach $40,000.