At that time, it would not be an exaggeration to say that the U.S. was essentially a "country of European immigrants." European Americans made up about 85% of the total population, with the majority coming from England, Ireland, Germany, Italy, Poland, and Scandinavia. There were not as many Hispanic or Asian populations as we see today.

However, after 100 years, the U.S. has become much more ethnically diverse. As of 2020, the percentage of European Americans (excluding Hispanics) has dropped to 57.8%. This is the lowest percentage since the U.S. Census began in 1790, and it has decreased rapidly compared to 63.7% just ten years ago in 2010. In 1990, it was 75.6%, meaning it has decreased by nearly 20% in just 30 years. The gap has been filled by a sharp increase in Hispanic (18.7%) and Asian (6.1%) populations.

Looking at it by generation, the change is evident. Among those aged 75 and older, whites still make up 77%, but among those aged 18-24, they account for only 50%. This indicates that younger generations are much more racially diverse. As the generations that will shape the future of American society come from more varied backgrounds, the racial composition will continue to change.

Another interesting change is interracial marriage. Since the 1967 U.S. Supreme Court ruling in Loving v. Virginia legalized interracial marriage, the rate of such marriages has steadily increased. As of 2019, about 19% of all marriages were interracial, resulting in a consistent rise in mixed-race populations. In 2008, the mixed-race population was about 52 million, or 5% of the total, which was a 33% increase compared to 2000.

There is also another interesting point regarding the change in the proportion of blue-eyed whites. Among whites born between 1899 and 1905, a staggering 57.4% had blue eyes. However, as of 2022, only 34% of the white population in the U.S. was found to have blue eyes. This means that the proportion of blue eyes has nearly halved over the past century. This can be seen not only as a genetic factor but also as a result of increased genetic diversity due to interracial marriage.

Of course, there are regional differences. For example, in areas where Northern Europeans have settled, the proportion of blue eyes is relatively high. In fact, in Iceland, 88% of the population has green or blue eyes, which is closely related to the distribution of European immigrants.

Ultimately, looking at the demographic composition of the U.S., it is clear that it is moving from a "white-centric society" in the past to a "multicultural society" today. The proportions of Hispanic, Asian, and African American populations will continue to rise, significantly impacting American society as a whole in politics, economics, culture, and education.

In other words, today's America has become so diverse compared to the early 1900s, and this diversity is the key driving force that makes the U.S. one of the most unique and dynamic countries in the world.