The first census to identify Native Americans occurred in 1860, and counted 339,421 Native Americans in the modern U.S. excluding Alaska. In 1900, the Native American population was approximately 237,000. This is a decrease of about 102,421, or 30.2% of the population in 1860, over the course of 40 years.
This decrease in population can be explained by a number of factors, including violent conflict between Native Americans and European colonizers and displacement of Native American populations. For example, in the mid-19th century, many Native American populations were pushed westward. Displacement from land and traditional ways of life resulted in higher death rates and increased infant mortality. The disruption in daily life caused by displacement and movement to reservations also decreased birth rates because of societal changes. Additionally, Native Americans often married European-descended Americans, and their children may not have been identified as Native American on census forms.