Between 1492 and 1890, the population of american indians in the continental u. s.:

The best answer is, decreased dramatically. 

Following the massive and consistent arrival of Europeans following the expeditions of Columbus in 1492, the American Indians were faced with devastation, disease, and death. Colonial settlers, the British, French, Spanish, and eventually American governments would all negotiate various treaties and agreements with the American Indians, however, these were often violated or negotiated in a way to leave the Indians in some kind of deficit. As the years passed and the tribes along the east coast were removed or assimilated, the American government enacted full-blown warfare against the American Indians in the mid-west and west, eventually forcing all remaining members into assimilation and reservations.