Yes, a passport (or other document/s required by DHS) reflecting identity and citizenship is required for one’s admission into the United States. This requirement came into effect on January 23, 2007, under the Western Hemisphere Travel Initiative (WHTI). Under the WHTI, all persons traveling by air between the U.S. and Canada, Mexico, Central or South America, the Caribbean, or Bermuda need valid passports, Air NEXUS cards, or U.S. Coast Guard Merchant Mariner Documents.