Travel as we've known it will change once again by the end of the year. If you're planning a Christmas holiday cruise to the Caribbean islands, for instance, your birth certificate and driver's license will no longer allow you to re-enter the United States if returning on Jan. 1, 2007, or after. Passport, please.

Why? According to the Web site of the U.S. Department of State (www.travel .state.gov), "The Intelligence Reform and Terrorism Prevention Act of 2004 mandated that the U.S. secretaries of State and Homeland Security develop and implement a plan to require U.S. citizens and foreign nationals to present a passport or other appropriate secure identity and citizenship documentation when entering the United States." Thus, the Western Hemisphere Travel Initiative was conceived.

The goal of the soon-to-be-effected initiative is to strengthen border security and facilitate entry into the United States for U.S. citizens and legitimate foreign visitors. It will apply to all travelers to and from Canada, Mexico, Central and South America, the Caribbean and Bermuda, who will be required to carry a passport or other accepted document that establishes the bearer's identity and nationality to enter or re-enter the United States.

For many years, U.S. citizens and some citizens of other countries in the Western Hemisphere, including Canadians and Mexicans, have not been required to present a passport to enter the United States. Other forms of documents, less secure than the passport, have historically been accepted. No longer.

The Western Hemisphere Travel Initiative will not affect travel between the United States and its territories. U.S. citizens traveling between the United States, Puerto Rico, the U.S. Virgin Islands, Guam, the Northern Mariana Islands and American Samoa will continue to be able to use established forms of identification to board flights and for entry.

Note this example, offered on the Department of State Web site: "A person may travel to and from the United States to the U.S. Virgin Islands without a passport or other secure document, but under the new regulations, a passport or other secure document would be required to re-enter the U.S. Virgin Islands from the British Virgin Islands or another country as of Dec. 31, 2006."

Customs and Border Protection, the unified border agency within the Department of Homeland Security, is charged with the management, control and protection of our nation's borders at and between the official ports of entry. CBP's further mission is to keep terrorists and terrorist weapons out of the country while enforcing hundreds of U.S. laws. This agency will assume primary responsibility for overseeing and enforcing the new initiative.

The Western Hemisphere Travel Initiative will be rolled out in phases, providing as much advance notice as possible to the public in order to enable travelers to meet the terms of the new regulations. The proposed timeline. according to the Department of State Web site, is: