In early 1800's, boys and girls were dressed alike in white
from birth through early childhood. Babies wore "long clothes" which
were white cotton dresses that extended beyond the length of the infants' body.
In the early twentieth century, ideas about child-rearing
changed, and developmental stages such as crawling were encouraged. Children's
clothing was adapted to allow for more movement and more colors were
introduced.
Originally, pink was designated for boys, as it was thought to
be the stronger color. In Christian tradition, red was associated as male, and
its ‘little’ sibling pink was used for boys. Blue was associated the Virgin
Mary and therefore considered feminine.
After WWI, blue was used extensively for men's uniforms.
Therefore, blue became associated as more of a masculine color. From the 1940's
onward, pink was pushed as a woman's color. "Think Pink" was the
marketing slogan to convince women to embrace their femininity. Dressing girls
in pink reinforced this role by conditioning with a set of rules that started
with little girls, made of "sugar and spice and everything nice."
Today, those gender specifications hold strong, with pink
designated for girls, and blue for boys.