Amazon announced on Thursday that it had cleared a significant legal obstacle and could now expand the service to additional areas of the United States thanks to official authority to fly its delivery drones farther without the requirement for ground spotters. Amazon used to have to keep its drones flying within a pilot’s visual range. With permission from the Federal Aviation Administration, Amazon is able to fly above the line of sight of an observer. The business said that it will increase the size of its delivery area in College Station, Texas, one of the test cities.