A passport's validity is generally determined by the applicant's age. In the US, passports issued for adults ages 16 and older are valid for 10 years. Children 15 years of age and under receive passports valid for 5 years. There are two primary exceptions to this rule: a second passport is valid for 2 years and an emergency passport is valid for 1 year. In some instances, when replacing a lost passport, for example, the Department of State may issue a passport with lesser validity (usually 1 or 2 years).