DHS now requires all travelers who enter the United States through land and sea ports to document their citizenship. This means that United States, Canadian and Bermudan citizens must present evidence of citizenship (such as a passport OR a birth certificate and photo identification) to enter the U.S. Persons, including U.S. citizens, who fail to carry one of these alternate sets of acceptable documents face a possible denial of entry and delay in being able to re-enter the United States.