Given the fragmentary nature of the evidence, even semi-accurate pre-Columbian population figures are thought 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. In 1992, Denevan suggested that the total population was approximately 53.9 million and the populations by region were, approximately, 3.8 million for the United State and Canada , 17.2 million for Mexico, 5.6 million for Central America, 3 million for the Caribbean, 15.7 million for the Andes and 8.6 million for lowland South America.