And so I did a little research and came up with nothing...... but this:
In the early 1900s it seems as though boys would dress as well as the teacher. They are wearing suits.
In 1947 only a few boys wore bib overalls.
This year there must have been a sale on bib ovealls at J.C.Penney
Overalls are usually made of denim and often have riveted pockets, similar to those on jeans. Bib overalls have long been associated with rural men and boys in the Southern United States and the Midwestern United States, especially farmers and railroad workers. They are often worn with no shirt at all by children, teen boys and men in warmer weather. All over America in modern times, painters, farmers, certain factory workers, some train locomotive engineers, carpenters and other tradesmen or workmen often wear overalls as protective over garments. Since the 1960's, different colors and patterns of bib overalls have been increasingly worn by young people of both sexes, often with one of the straps worn loose or unfastened along the side and under the arm. The bib overalls fashion trend among American youth culture peaked in the latter half of the 1970s, and again for females in the late 1990s.
In the 20th century, overalls were also sometimes worn as casual clothes, due to their comfort, handiness and durability. Overalls are also made in corduroy in addition to denim, and come in many styles.
In British English such bib type overalls are usually called pairs of dungarees.