C-1 visa:

C-1 visas are applicable to aliens passing in immediate and continuous transit through the United States.

Immediate transit is defined as a reasonably expeditious departure in the normal course of travel as the elements permit and a prearranged itinerary assumes.

The C-1 visa holder is required to possess a ticket or other indicia of transportation to his/her destination and is also required to obtain a letter from the shipping company pledging to pay costs of removal if necessary. The beneficiary also needs to possess adequate funds for the transit and permission to enter the third country.

The period of stay is limited to 29 days.

Waiver:

US immigration law allows for the waiver of the C-1 visa requirement for a person in immediate and continuous transit through the United States on an authorized carrier if the person is otherwise admissible, there is a confirmed onward reservation to the next country, and the journey is continued on the same or connecting line within 8 hours or the next available transport. The alien cannot, however, change carriers more than twice.