Final answer:
The U.S. population growth rate over the past 30 years has been about 1% annually, influenced by a higher fertility rate and positive net migration.
Step-by-step explanation:
Over the past 30 years, the United States has experienced a population growth rate of about 1% annually. This rate is considered moderate compared to the global context, where some regions face much higher growth rates. The U.S. growth is attributed to a combination of factors such as a higher fertility rate, at about 2.1, and a positive net migration rate. Furthermore, the demographic shift includes an increase in the elderly population, with those over 65 years old now making up a larger percentage of the U.S. population.
The aging population, now often referred to as "the graying of America", is one of the key demographic trends, alongside the steady urbanization of the population over the last century. It’s important to note that the United States has an intermediate fertility rate, which is expected to result in a 26 percent population growth for countries in this category, according to United Nations predictions.