Notes
This is likely part of the U.S. Navy Undress White uniform, which was the standard-issue warm weather uniform used during World War I. It was also commonly called the "Crackerjack" uniform, which arose from its similarity to the uniform worn by the mascot of the Cracker Jack snack brand, Sailor Jack. These jumpers were made out of breathable cotton. The wide collared, pullover design was intended to allow a sailor to quickly remove the shirt if he were to go overboard. The insignia on the left sleeve indicates that the wearer was a petty officer second class, working as an aviation maintenance technician.