Following an incident in 2005 where a balloon knocked over a street light and injured spectators (see § Injuries), new safety measures were incorporated in 2006 to prevent accidents and balloon-related injuries. One measure taken was the installation of wind measurement devices to alert parade organizers to any unsafe conditions that could cause the balloons to behave erratically. In addition, parade officials implemented a measure to keep the balloons closer to the ground during windy conditions. New York City law prohibits Macy's from flying the full-size balloons if sustained winds exceed 20 knots (23 mph) or wind gusts exceed 30 knots (35 mph); New York's tall buildings and mostly uniform grid plan can amplify wind velocity on city streets. This law, imposed in 1997, has never been activated, despite several close calls; the only time the parade balloons have ever been grounded was 1971. Each balloon has its own risk profile to determine handling in windy conditions; taller, upright balloons are rotated so that they appear horizontal and facing downward in such situations (as was the case in 2019, when a grounding was narrowly averted). In the event the balloons are grounded, the remaining floats and performances would continue as scheduled.