Effective January 31, 2008, the Department of Homeland Security (DHS) and the Department of State (DOS) will require all adult travelers to present proof of citizenship and proof of identity when entering the United States through land and sea ports-of-entry. This requirement implements Phase 2 of the Western Hemisphere Travel Initiative (WHTI). The WHTI was developed in response to the mandate contained in the Intelligence Reform and Terrorism Prevention Act of 2004 which requires all travelers to present a passport or other acceptable document in order to enter the United States. Phase 1 of the WHTI became effective on January 23, 2007 and requires all individuals (including U.S. citizens and Canadian citizens) traveling by air to the United States to present a valid passport, Air Nexus card U.S. Coast Guard merchant mariner document, or Alien Registration Card, if applicable