Birthday celebrations in America crossed over the line between a few rich and celebrated individuals to the rest of us, sometime around 1860 – 1880. We can thank two factors for this change in emphasis.
Children became seen less for their economic necessity, as workers, and valued more emotionally, as individuals and as beloved family members. Therefore, worthy of celebration for just being alive.
Also, the production of household and workplace clocks became widespread, quite a change from the rare clock of the preindustrial period. The clock along with the time focus of factory work and the like, street cars etc., made Americans much more time conscious.
Because of these major shifts in American life, birthday celebrations became a national tradition by the early 20th century. The Happy Birthday song was popularized, in unauthorized versions, sometime right before 1914 to 1934.
