Source: http://www.npr.org/sections/money/2014/0...

In 1926, Congress created what we now call the FAA, and declared that the air above 500 feet is the public domain. But what about the air below that?

...

Causby sued the government, and the case went all the way to the Supreme Court. In the end, the court sided with Causby, ruling that landowners own the sky above their homes up to at least 83 feet.

But the decision still left a gap. If the air above 500 feet is public property, and the air below 83 feet is private property, what about the space in between?

This is the territory that entrepreneurs dreaming of drones have their eyes on.