Nobody is sure what the population of the Americas was before Columbus arrived in 1492, let alone the territory that is today the United States. Estimates vary wildly, but it seems to be accepted that the indigenous population of the Americas (the continents of North and South America combined) was between 50 million and 100 million in the 1490s. That includes approximately 15 million people living in the Aztec Empire and around 6 million Inca. The population of North America at the time is equally uncertain, and has been estimated at between 5 and 15 million.
Indigenous populations were hit hard by the arrival of European settlers. Firstly they were attacked by disease - some historians believe that over 50% of the population was killed by diseases including smallpox. And yet more were killed by wars, massacres and resettlement programmes. The Native American population of the United States reached a low point in the early 20th century, but has since been gradually increasing.
Formal census were not carried out during the colonial era, but records show that the colonial population grew from a shaky start of just 3,800 in 1610 to over 1 million in 1750. The population grew rapidly from then onwards and, when the first official census was held in 1790, shortly after independence, the population had grown to 3,929,214.
