Native Americans in the United States are the indigenous peoples in North America within the boundaries of the present-day continental United States, Alaska, and the island state of Hawaii. They are composed of numerous, distinct Native American tribes and ethnic groups, many of which survive as intact political communities. The terms used to refer to Native Americans have been controversial. According to a 1995 U.S. Census Bureau set of home interviews, most of the respondents with an expressed preference refer to themselves as American Indians (or simply Indians – see Native American name controversy), and this term has been adopted by major newspapers and some academic groups; however, this term does not typically include Native Hawaiians or certain Alaskan Natives, such as Aleut, Yup'ik, or Inuit peoples.

Since the end of the 15th century, the migration of Europeans to the Americas, and their importation of Africans as slaves, has led to centuries of conflict and adjustment between Old and New World societies. Europeans created most of the early written historical record about Native Americans after the colonists' immigration to the Americas. Many Native Americans lived as hunter-gatherer societies and told their histories by oral traditions. In many groups, women carried out sophisticated cultivation of numerous varieties of staple crops: maize, beans and squash. The indigenous cultures were quite different from those of the agrarian, proto-industrial, mostly Christian immigrants from western Eurasia. Many Native cultures were matrilineal; the people occupied lands for use of the entire community, for hunting or agriculture. Europeans at that time had patriarchal cultures and had developed concepts of individual property rights with respect to land that were extremely different.

The differences in cultures between the established Native Americans and immigrant Europeans, as well as shifting alliances among different nations of each culture through the centuries, caused extensive political tension, ethnic violence and social disruption. The Native Americans suffered high fatalities from the contact with infectious Eurasian diseases, to which they had no acquired immunity. Epidemics after European contact caused the greatest loss of life for indigenous populations. Estimates of the pre-Columbian population of what today constitutes the U.S. vary significantly, ranging from 1 million to 18 million.

After the colonies revolted against Great Britain and established the United States of America, President George Washington and Henry Knox conceived of the idea of "civilizing" Native Americans in preparation for assimilation as U.S. citizens. Assimilation (whether voluntary as with the Choctaw, or forced) became a consistent policy through American administrations. During the 19th century, the ideology of manifest destiny became integral to the American nationalist movement. Expansion of European-American populations to the west after the American Revolution resulted in increasing pressure on Native American lands, warfare between the groups, and rising tensions. In 1830, the U.S. Congress passed the Indian Removal Act, authorizing the government to relocate Native Americans from their homelands within established states to lands west of the Mississippi River, accommodating European-American expansion.

The first European Americans to encounter the western interior tribes were generally fur traders and trappers. There were also Jesuit missionaries active in the Northern Tier. As United States expansion reached into the American West, settler and miner migrants came into increasing conflict with the Great Basin, Great Plains, and other Western tribes. These were complex nomadic cultures based on horse culture and seasonal bison hunting. They carried out strong resistance to United States incursions in the decades after the American Civil War, in a series of Indian Wars, which were frequent up until the 1890s, but continued into the 20th century. The transcontinental railroad brought more non-Natives into tribal land in the west. Over time, the U.S. forced a series of treaties and land cessions by the tribes, and established reservations for them in many western states. U.S. agents encouraged Native Americans to adopt European-style farming and similar pursuits, but European-American agricultural technology of the time was inadequate for often dry reservation lands. In 1924, Native Americans who were not already U.S. citizens were granted citizenship by Congress.

Contemporary Native Americans have a unique relationship with the United States because they may be members of nations, tribes, or bands with sovereignty and treaty rights. Since the late 1960s, Native American activism has led to the building of cultural infrastructure and wider recognition: they have founded independent newspapers and online media; FNX, the first Native American television channel (2011), community schools, tribal colleges, and tribal museums and language programs; Native American studies programs in major universities; and national and state museums. Native American and Alaskan Native authors have been increasingly published; they work as academics, policymakers, doctors, and in a wide variety of occupations. Cultural activism has led to an expansion of efforts to teach and preserve indigenous languages for younger generations. Their societies and cultures flourish within a larger population of descendants of immigrants (both voluntary and involuntary): African, Asian, Middle Eastern, European, and other peoples.