The Law relating to Air Commerce has been laid down in Title 49, Subtitle VII of the US Code.
The term air commerce as defined in the US Code is as follows:
"Any foreign air commerce, interstate air commerce, the transportation of mail by aircraft, the operation of aircraft within the limits of a Federal airway, or the operation of aircraft that directly affects, or may endanger safety in, foreign or interstate air commerce."
The term air transportation has been defined as any “foreign air transportation, interstate air transportation, or the transportation of mail by aircraft.”
The United States Government has sovereign jurisdiction over the airspace of the US.
Similarly, a US citizen has a right of transportation through the navigable airspace of the US.
(More : http://www.law.cornell.edu/uscode/html/uscode49/usc_sup_01_49_10_VII_20_A.html )