The idea that everyone should celebrate their birthday is, weirdly, not very old itself.
Not until the 19th century—perhaps around 1860 or 1880—did middle-class Americans commonly do so, and not until the early 20th century were birthday celebrations a tradition nationwide. In fact, the song “Happy Birthday” is not far beyond its own 100th birthday.
Throughout history there are scattered examples of birthday festivities around the globe, but the honorees tended to be either rulers, such as Egyptian pharaohs, or powerful members of an upper class. For a while, a similar pattern held in the United States: Birthdays were for rich people or national heroes. Americans celebrated George Washington’s birthday, for instance, but for everyone else, a birthday—if they even knew the date—was just another day.
The shift in the mid-19th century started with kids. Some scholars have emphasized the increased attention that began to be lavished on individual children as families started having fewer of them. Kids’ birthday parties may have been an early hint of how American children were starting to be viewed as less valuable economically (as workers) and more valuable emotionally (as family members).
The rise in birthday celebrations was also part of a larger shift in how people conceptualized the passing of time. Clocks in preindustrial America were “rare and seldom accurate,” according to the historian Howard Chudacoff. As the 19th century progressed, the widespread production of household clocks and pocket watches made it possible for Americans to constantly know what time it was. And as more people followed the schedules of factories, streetcars, and trains, they had more reason to watch those clocks.
As Americans became more aware of time, they also became more aware of how it passed in their own lives, Chudacoff argues in his 1989 book, How Old Are You?: Age Consciousness in American Culture. This newfound focus on age was visible in many 19th-century institutions: Schools started using age to separate students into grades, and doctors started using it to assess people’s health and development. Not coincidentally, this was the same era when people started noting their birthday.