When entering the United States, entrants must present a passport, e-passport or participate in the U.S. Customs and Border Protection's trusted traveler programs for low-risk visitors, explains FindLaw. Instead of a passport, U.S. citizens can present a U.S. Merchant Mariner document if on official business, a U.S. military ID with travel orders or a NEXUS card at airports with NEXUS kiosks.
Declaration is required when entering the United States for any items purchased in Mexico or Canada, according to U.S. Customs and Border Protection. As of 2015, an $800 exemption is in place for gifts and personal items, inclusive of 1 liter of alcohol per 30 days for individuals over age 21. Since states have the ability to regulate alcohol distribution and sales, restrictions vary widely between states, and each border entry point may operate differently.
There are some restrictions on medications imported into the United States, so individuals with medication should inquire with U.S. Customs and Border Protection prior to entry, notes the agency. Cuban cigars may not be brought into the country, nor can any illegal drugs be transported across the border. Consequences for any amount of an illegal drug may include fees, imprisonment, a federal record or relinquishment of a vehicle. Any items made from an endangered species are prohibited.
Most agricultural products cannot be brought into the United States due to concern about the transmittal of pests or diseases that may harm the environment or human health, states the U.S. Department of Agriculture.