Archaeological discoveries in the United States in the second half of the eighteenth century and the first quarter of the nineteenth century relate predominantly to Native American earthworks discovered as Americans expanded into the Ohio and Mississippi River valleys and the interior Southeast. American settlers, naturalists, and antiquarians recorded these earthworks and puzzled over the question of who had built them and when. By the start of the nineteenth century, a growing national interest in science and America's unique ancient history led to an increase in the collection and synthesis of data, to publication, and to a spate of theories on the origins of the people who built the earthworks.
The earliest archaeology focused on the detailed mapping of ruins. In laying out the town of New Philadelphia, Ohio, in 1772, missionary David Zeisberger described the Indian mounds that the new town would soon obscure. That same year, the Grave Creek Mound was discovered by settlers near Wheeling, Virginia (later West Virginia). This mound was left intact, a relatively rare occurrence for the time, and more than 230 years later it could still be seen surrounded by the town of Moundsville. In 1787 General Rufus Putnam of the Ohio Company of New England prepared a detailed map of the ancient monuments near the new town of Marietta, the first such map ever made in the United States. Another first at Marietta occurred when Manasseh Cutler (1742-1823) pioneered the use of tree rings to date archaeological sites. He concluded that the mounds were at least one thousand years old.
Synthesis and interpretation of such individual archaeological reports began in 1787, when Benjamin Barton published a study of Ohio mound sites and drew a conclusion that would become common in this era—that the mounds could not have been built by American Indians or their ancestors, but were built by a separate race of people who were later displaced by Indians. Such theories, which attributed the construction of the mounds to various people such as the Vikings, Phoenicians, Israelites, and Toltecs, came to be called the "myths of the mound-builders." The idea that the sophisticated, monumental earthworks were beyond the intellectual and engineering skill of North American Indians had currency among American scholars from the late eighteenth century until the late nineteenth century. A century later these earthworks were known to have been built by the ancestors of contemporary Native Americans and were constructed from 3,000 b.c. to as late as the early eighteenth century a.d.
compelling evidence for this cultural continuity began to form as early as the late eighteenth century. Natural historian William Bartram (1739-1823) traveled extensively throughout the southeastern United States and published descriptions of mound sites located in the territories of the Creek, Choctaw, and Cherokee tribes. At one then-functioning Indian town in Florida, Bartram observed the practice of Indians building and using mounds. Yet at other towns, Indian people could not identify the mound builders. Given this, Bartram concluded the mounds had been built by ancestors of the Indians. Unfortunately, his work was not widely distributed at the time and did little to offset the enthusiasm for interpreting the mounds as the work of non-Native American cultures.
Archaeology as the science of excavation began in the United States in 1784 when Thomas Jefferson formally excavated an Indian mound near Charlottesville, Virginia, and published the results of his study in a chapter of his widely-read book, Notes on the State of Virginia (1785). Jefferson pioneered scientific and problem-oriented archaeology in the United States as his excavation was not designed to recover objects for display, but rather to answer questions about the reasons the mound was constructed. Jefferson considered as alternative hypotheses that it was either a place where warriors had died in battle and were interred in a single event or a common sepulcher for a community, used over many generations. The presence in the mound of the remains of both males and females and small children, and the absence of evidence of traumatic injury, led Jefferson to conclude it was a community cemetery used over many generations. Few formal, scientific excavations followed directly on Jefferson's, although his published report and interest in Indian mounds spurred much new study of such archaeological sites.
In 1799, as president of the American Philosophical Society, Jefferson sent a letter to correspondents urging them to collect precise data on the form and content of fortifications, tumuli, and other Indian works of art. The letter called for cuts to be made into the tumuli to determine their contents. In the late eighteenth and early nineteenth centuries, the Transactions of the American Philosophical Society became a source of information concerning America's antiquities. The most famous of these early reports is that by Henry M. Brackenridge in 1818, which included descriptions of mounds beyond Ohio, most notably the site of Cahokia near St. Louis, the largest mound complex in North America. This period of early American archaeology was influenced by European studies of ancient sites such as Stonehenge, Avebury, and countless less familiar barrows (mounds) spread across the English countryside. Archaeological studies of the ruins of Greece, Rome, and Egypt were rarely compared to the earthen structures built by Native Americans north of Mexico. Significant exceptions include Jefferson's comparison of the unusual burial practices he observed in the Virginia burial mounds to strikingly similar mortuary customs of ancient Greece, and Henry M. Brackenridge's likening of the Cahokia mounds near St. Louis to the pyramids of Egypt.
Archaeology in the United States in the early nineteenth century remained the concern of antiquarians, amateurs committed to gaining knowledge, but not profit, through the study of ancient sites and ancient objects. The American Antiquarian Society (1812), a group of wealthy New Englanders committed to investigating and collecting American antiquities, was the most important of these and invited representation from all states in the Union. In 1820 the society funded and published the results of a large, important study of Ohio antiquities by Caleb Atwater. The engagement of the federal government in the study and preservation of America's antiquities was still a half-century to a century away (with the Smithsonian and the National Park Service, respectively), and America's universities would not engage in the study of American Indian archaeological sites until the last two decades of the nineteenth century.