According to the U.S. national aviation authority, the flying drone is legal in USA but need to follow some compliant as below:
Special Travel Considerations for Foreigners: You need to register your drone. Don’t forget to use the QR code if you want to see what’s available at hobby registration. If you’d like to contact the FAA directly before you travel with any questions you might have, here is their contact information: UAShelp@faa.gov / +1 866 835-5322. If you fly for work, you need to collect a certificate. For fun, need to maintain hobbyist flying norms.
General rule: You can fly for hobby and recreation only. The weight of the drone must be below 55 lb. The drone must be a visual line of sight. The flying line must be between one-half of the surface area of a building or place that contains more than half an acre (25 000 m2) during daylight hours with unobstructed views over open spaces; it cannot reach any part from where it is pointed except by means at least 7 feet high upwind. A landing strip approximately 2 x 1 foot square in size may be placed inside said buildings under conditions prescribed. Avoid general parks, military areas,s, and tall buildings.
Commercial rule: Drone need to be registered. Fly height is below 400 ft. Speed will be under 100 miles per hour. For such, you need to pass Aeronautical Knowledge Test. Collect FAA manual for compliance and certification.