As the world's population is approximately 6.8 billion, the current United States population represents a mere 4.5% of the world's population so about one in every twenty people on the planet is a resident of the United States of America.
In 1790, the year of the first census of the U.S.A. population, there were 3,929,214 Americans. By 1900, the U.S.A. population jumped to 75,994,575. In 1920 the census counted more than a hundred million people (105,710,620). Another 100 million people were added to the United States population in just fifty years when the two hundred million barrier was reached in 1970 with 203,302,031 counted in the census.
The 2000 Census counted a U.S.A. population of 281,421,906. Six years later the U.S. population had grown to 300 million. At 7:46 a.m. (Eastern Time) on Tuesday, October 17, 2006 the U.S. Census Bureau estimated that the United States population officially reached 300 million.
The U.S. Census Bureau expects the U.S.A. population to grow to reach these estimates over the next few decades:
- 2010 - 307,745,538
- 2020 - 336,031,546
- 2030 - 363,811,435
- 2040 - 392,172,658
- 2043 - 400,527,776 (the year of 400 million)
- 2050 - 420,080,587
The Population Reference Bureau succinctly summarized the state of the growing U.S.A. population in 2006, "Each 100 million has been added more quickly than the last. It took the United States more than 100 years to reach its first 100 million in 1915. After another 52 years, it reached 200 million in 1967. Less than 40 years later, it is set to hit the 300-million mark. Within another 37 years, we are projected to pass 400 million."
In 2050, the United State population will remain the world's third largest (with India as number one and China as number two). Number four Nigeria is expected to have more than 120 million fewer people than the U.S. population in 2050.
The United States' total fertility rate is 2.1, which means that, on average, each woman gives birth to 2.1 children throughout her life. The total fertility rate of 2.1. means a stable no-growth population overall. However, immigration plays a huge impact on the growing U.S. population. Overall the United States population is growing at 0.9% a year as of 2007.