Re:MIT’s gas-powered drone is able to stay in the air for fi...
by vilhelm_s on Wednesday June 28, 2017 @01:51AM
(#14651983)
Not to mention outside Washington DC. :)
https://www.washingtonpost.com/news/the-switch/wp/2015/10/28...
And before that, I believe surveillance blimps have been used in some form or another since the 19th century.