[Lurking Libertarian]

I travelled on my mother’s passport as a child in the 1960s, but she had to have me added to her passport at the Passport Office.

[faucetman]

I traveled on my older sister’s passport in 1955, BUT in 1961 I had MY OWN U.S. Passport. In 1955 she was only 8 yrs/11 mos old, I was 5. Must be 5 was too young and 8 or certainly 11 was old enough for your own passport back then.