Do U.S. citizens and nationals need to prove to their employers that they are eligible to work?

Yes. While citizens and nationals of the U.S. are automatically eligible for employment, they too must present proof of employment eligibility and identity, and complete an Employment Eligibility Verification form (Form I-9). Citizens of the U.S. include persons born in Puerto Rico, Guam, the U.S. Virgin Islands, and the Northern Mariana Islands. Nationals of the U.S. include persons born in American Samoa, including Swains Island.