Finding that an entry visa to the United States has been granted is cause for great celebration for most applicants, but that celebration is often premature: Visas allow travelers to board their transportation to the U.S., but they by no means guarantee entry. You cannot stay in the U.S. at all with a visa alone. Determining officers of the Department of Homeland Security at the U.S. port of entry are empowered to turn away even people with visas and send them back where they came from if they sense some subterfuge or illegal intent.
The Visa Waiver Program
The Visa Waiver Program allows nationals of nations that are part of the Western Hemisphere Travel Initiative to enter the U.S. port of entry without a visa. The Visa Waiver Program paperwork is handed out on the transport to be completed by each eligible person; if security checks at the U.S. port of entry do not flag the traveler for any reason, entry is typically granted for a period not to exceed 90 days. Entry is granted on several strict conditions, the two most important of which are that the traveler has in their possession a return trip ticket to their country of origin or another country outside U.S. territory, and that the traveler will not seek or perform work, either paid or unpaid.
The I-94 Card
The visa or the completed Visa Waiver Program document permits non-immigrant travelers to enter upon U.S. soil only to the extent that they can present themselves to a determining Department of Homeland Security official. The official and his work station are euphemistically referred to as “the gate.” The document that demonstrates permission to enter the country has been granted is universally called an I-94 -- the proper term is Arrival/Departure Record -- and it is issued by the determining officer at the gate. In simple terms, the visa allows the traveler to knock on the door; the I-94 card is proof the Department of Homeland Security has allowed them to come in. The I-94 determines the time limit of the stay, and the restrictions imposed upon the visitor while in the U.S. Visas do not allow any stay of any length within the U.S.
Most Common Types of Visas
The B1 professional and B2 tourist -- pleasure travel -- visas are typically issued for six-month periods, but the length is entirely within the decision-making process of the officer who happens to get the case, inspect the application and make the determination. Again, the length of time printed on the visa does not determine how long the visitor may stay in the U.S. Rather, it determines how long the visitor has to make the journey to the U.S., where the I-94 document may or may not be issued that details the length of the stay.
At the Gate
The unofficial posture is that few people can afford to live without working for more than six months. Because people coming to the U.S. on B2 visas are not allowed to work, they will in all likelihood be issued a maximum six-month I-94. If the entrant is seeking medical treatment that may quite reasonably be expected to take more than six months, the determining officer can issue a one-year I-94 without consulting a supervisor. A traveler with a B1 professional visa, meaning they have work the State Department has already determined is acceptable under all its conditions, can stay up to three years on a single I-94. In an extreme circumstance, then, a person with a one-month B1 visa could legally stay in the USA for three years, not one month.