At the moment, about 328 million people are living in the U.S, a nation that’s 9.84 million sq km (3.53 million square miles). But during the country’s history, these numbers haven’t stayed fixed.
Population density map of what is now the United States (1492)
It isn’t easy to evaluate populations in the 15th century in America. Most indigenous people lived in small communities. But beginning in the 19th century, archaeology and the research of burials and the material remains of society helped determine native populations before European contact.
Approximations for North America have ranged from 3.8 million to 18 million. Most of the indigenous tribes of America lived along the rivers and on the coasts of the Atlantic and Pacific oceans.
The Americas’ peoples had no resistance to Europeans’ diseases because the Americas’ populations had been primarily isolated from Europe. In that time, many deadly diseases evolved in the Old World (smallpox, the plague, measles). As a result, many indigenous peoples died from disease than in war with Europeans.
Animated map of population density in the U.S. (1790 – 2010)
The animated map of population density, made using Jonathan Schroeder’s county-level decadal estimates. Populations for intermediate years were interpolated by cubic splines to log-density; essentially, that means that it assumes a smooth change in the rate of growth for each county over time.
The map below shows when each state reached its highest point as percentage of the U.S. population.
Throughout the nineteenth century, more than one square mile (1.6 million km2) of land west of the Mississippi River was obtained by the federal government. This event led to Westward Expansion.
Population Density of the U.S. in Six Degrees (1890)
Until the 20th century, the eastern states remained the most populous. But over the past century, the distribution of the population in the nation has changed dramatically. So in 1917, only 3.1 million people lived in California. After 100 years, the population of California increased by 504% to 39.9 million. Currently, the three most populous states in the US are California (39.5m), Texas (28.3m), and Florida (21m).
At present, the population’s median center continues to move to the southwest slowly (2.57 miles per year).
Animated map of population density in the U.S. (1990 – 2017)
Residents per square mile
1800 – 6.1
1850 – 7.9
1900 – 21.5
1950 – 42.6
2000 – 79.6
2017 – 92.2