If you exclude the deaths of indigenous people from between 1492 and 1900 from diseases brought over by European and Asian migration such as influenza, pneumonic plagues, cholera, and smallpox, the more realistic number of killed indigenous people is closer to 400,000-500,000.
If I remember correctly, the census figures for 1890 was around 270,000, down from an estimated 600,00 around 1860 who lived in the areas of the continent that would become the U.S.