US Citizens do not need a passport to travel between the United States and Puerto Rico. Travel between the United States and Puerto Rico will not be affected by the Western Hemisphere Travel Initiative. U.S. citizens traveling between the United States and Puerto Rico will continue to be able to use established forms of identification to board flights and for entry.
If traveling outside of the United States or a U.S. territory, a passport or other secure document will be required. For example, a person may travel to and from the United States to Puerto Rico without a passport or other secure document, but under proposed regulations, a passport or other secure document would be required to re-enter Puerto Rico from the British Virgin Islands, The Dominican Republic, St. Maarten or another country as of December 31, 2005.
More information is available at www.travel.state.gov.