Growth in America

America’s population is growing faster than that of most other developed countries, thanks to a combination of factors. The most important are births and deaths, plus domestic and international migration (i.e., people moving into or out of a state).

During the COVID-19 lockdown, immigration slumped and may not rebound to pre-pandemic levels. In addition, the aging population will likely slow future growth rates. Still, the United States remains a young country. One-fifth of its population is under age 15, compared to less than a one-seventh for Japan.

The most significant differences in America population growth between states are the result of birth and death rates and domestic migration, which can have a dramatic impact on a region’s demographic profile. Birth and death rates are influenced by a variety of factors, including economic conditions, education, health-related behaviors, and religious/cultural/political attitudes. Life expectancy also influences trends in population growth, with longer lifespans reflecting medical advances, better sanitation and nutrition, access to safe drinking water, and the reduction of disease vectors such as mosquitoes.

Population Growth in America

Births and deaths account for most of the population change in any given year. Counties can also grow through migration, where more people move into a county than move out (i.e., net migration). These factors are illustrated in a state’s annual population estimates, collected by OFM.

A state’s ranking in terms of its population size is an important measure of success and power, since seats in the House of Representatives are apportioned to states based on their population. For example, since 1998, Texas has gained eight seats and Florida has gained five — the latter passing New York as the nation’s third-largest state in 2014.

Different birth rates are the largest factor determining which states will grow the most and least. But the rank of a state’s population growth is also influenced by its geographic location, as a result of differing rates of immigration.

Between 2000 and 2021, the fastest-growing state was Arizona, followed by Florida. But the largest population gains were in multiple metro areas within Texas and Florida, including Dallas-Fort Worth and Houston, as well as two MSAs in southern California.

The population of America is one of the most dynamic and diverse in the world, reflecting a complex tapestry of history, migration, and cultural influences. As of the latest data available, the population of the United States stands at over 331 million people, making it the third most populous country globally, behind China and India. This vast populace encompasses a myriad of ethnicities, languages, religions, and lifestyles, contributing to the rich mosaic that defines American society.

In the same period, West Virginia lost population, as did four other states (New York, Illinois, Louisiana and Mississippi). Idaho and Nevada ranked highest in percentage growth, with Idaho up 2.1% and Nevada up 1.7%. Between 2020 and 2021, half of all states and three-fourths of counties had more deaths than births, a pattern indicative of an aging population. Domestic migration accounted for most of the variation in population growth between states, with the exception of West Virginia.