Pentagon testing mass surveillance balloons across the US
www.theguardian.com
Exclusive: the high-altitude balloons promise a cheap monitoring platform that could follow multiple cars and boats for extended periods

Article feom three years ago.

Credit to https://twitter.com/sphinxhaven/status/1621473569204015105?s=46&t=yBkgS7E-HwcqEdtmxmRqoA

Up to 25 unmanned solar-powered balloons are being launched from rural South Dakota and drifting 250 miles through an area spanning portions of Minnesota, Iowa, Wisconsin and Missouri, before concluding in central Illinois.