Passports are required in order to cross international borders, while visas are required in order to remain inside of a foreign country. In order to apply for a visa, you must have a passport. If you have lost your passport or if your passport has expired during your stay in the United States, you can apply for a new one through the embassy or consulate general of your nation of citizenship. If, however, you do not have a visa and passport and entered the country illegally or by using a false passport, you can and will be detained and deported from the United States if you are discovered or try to leave.
Loss, theft or expiration of your passport while inside of the United States does not make you an illegal immigrant. If anything should happen to your passport, immediately contact the embassy or consulate general of your birth country in the U.S. for replacement or renewal instructions. You must have a passport in order to travel domestically in the U.S. and in order to leave the U.S. or you risk detention and questioning by Homeland Security.
Carrying of documents
The U.S. Department of Homeland Security requires all aliens to carry their travel documents with them when travelling domestically inside of the country. You do not need to have your passport on hand if you are going to the grocery store; however, if you are flying from New York to Seattle, you must have your passport with you or you risk detention and questioning until your status is verified. Deportation can only occur after a hearing in an immigration court, you cannot simply be immediately stuck on a plane back to your home country while at the airport for not having your passport at hand.
If you entered the U.S. illegally without a passport or by using a false passport and are discovered by an inspecting agent or at the time of departure, you will be detained (imprisoned) for a period of time and subsequently deported. The lack of a passport will not deter your deportation. When released, an entry permit will be issued by your nation of citizenship for you to enter your country. Once deported, an illegal immigrant is banned from re-entering the United States for a designated period of time.
The only way to avoid detainment and deportation when leaving the United States as an illegal immigrant with no passport is to obtain a limited passport from an embassy or consulate general. Only the consulate of your nation of citizenship can issue you a limited passport card that will allow you to leave the U.S. and enter your country. Procedures and policies vary for every nation and must be obtained individually through the appropriate consulate. Though a limited passport prevents deportation, it does not prevent banishment from the U.S. for a designated period of time.