A mix of various documents can be presented to, for instance, verify one's legal eligibility to take a job within the US. "Identity" and "citizenship" is established by presenting a passport alone, but this must be accompanied by a Social Security card for taxation ID purposes. A driver's license/state ID establishes "identity" alone, but does not establish "citizenship", as these can be provided to non-citizens as well. In this case, an applicant without a passport may sign an affidavit of citizenship or be required to present a birth certificate. They must still also submit their Social Security number.