The population figure for indigenous peoples in the Americas before the 1492 voyage of Christopher Columbus has proven difficult to establish. Scholars rely on archaeological data and written records from settlers from the Old World. Most scholars writing at the end of the 19th century estimated that the pre-Columbian population was as low as 10 million; by the end of the 20th century most scholars gravitated to a middle estimate of around 50 million, with some historians arguing for an estimate of 100 million or more. Contact with the New World led to the European colonization of the Americas, in which millions of immigrants from the Old World eventually settled in the New World.
The population of African and Eurasian peoples in the Americas grew steadily, while the indigenous population plummeted. Eurasian diseases such as influenza, bubonic plague and pneumonic plagues devastated the Native Americans who did not have immunity to them. Conflict and outright warfare with Western European newcomers and other American tribes further reduced populations and disrupted traditional societies. The extent and causes of the decline have long been a subject of academic debate, along with its characterization as a genocide.
Given the fragmentary nature of the evidence, even semi-accurate pre-Columbian population figures are impossible to obtain. Scholars have varied widely on the estimated size of the indigenous populations prior to colonization and on the effects of European contact. Estimates are made by extrapolations from small bits of data. In 1976, geographer William Denevan used the existing estimates to derive a "consensus count" of about 54 million people. Nonetheless, more recent estimates still range widely.
Using an estimate of approximately 37 million people in Mexico, Central and South America in 1492 (including 6 million in the Aztec Empire, 5-10 million in the Mayan States, 11 million in what is now Brazil, and 12 million in the Inca Empire), the lowest estimates give a death toll due from disease of 90% by the end of the 17th century (nine million people in 1650). Latin America would match its 15th-century population early in the 19th century; it numbered 17 million in 1800, 30 million in 1850, 61 million in 1900, 105 million in 1930, 218 million in 1960, 361 million in 1980, and 563 million in 2005. In the last three decades of the 16th century, the population of present-day Mexico dropped to about one million people. The Maya population is today estimated at six million, which is about the same as at the end of the 15th century, according to some estimates. In what is now Brazil, the indigenous population declined from a pre-Columbian high of an estimated four million to some 300,000.