About the Transit Visa - USA Only - C1,C2,C3 category

Generally, a citizen of a foreign country who wishes to enter the United States must first obtain a visa, either a nonimmigrant visa for temporary stay, or an immigrant visa for permanent residence. Transit © visas are nonimmigrant visas for persons traveling in immediate and continuous transit through the United States enroute to another country, with few exceptions.

If you already have a valid visitor (B) visa, you may be able to use it to transit the United States. If you are a citizen of a participating country, you may be able to transit the United States on the Visa Waiver Program.