The Western Hemisphere Travel Initiative ("WHTI") requires travelers to present a passport or other approved secure document denoting citizenship and identity for all land and sea travel into the United States starting on June 1, 2009. Citizens of Canada, the United States and Bermuda are currently exempt. Therefore, U.S., Canadian and Bermudan citizens should apply for secure passports or renew passports or investigate obtaining other acceptable secure documents such as special passport cards and trusted traveler cards that DHS has developed. Additional information about WHTI is available here.