The gates at the Circuit of the Americas will not open before 10 am local time, the time when Free practise # 3 was scheduled to begin.
The FIA regularities do not necessarily take care about free practises being held. Rumours have it that even the qualiying for the Grand Prix of the USA will be cancelled for today and will probably be made up tomorrow morning before the scheduled race.
Funny enough, if no qualiying is held tomorrow, the ranking of free practise would define the grid - means free practise # 1 in this case.