The town had as many as 1,000 inhabitants inside the walls at its peak, and included a complex of thirteen earthen mounds, hundreds of home sites, a palisade (stockade), and other structures.

The historic site continues to preserve and relate the story of pre-contact Middle Mississippian indigenous culture on the Ohio River.

In 1938, the Indiana Historical Society, with funding from Eli Lilly, purchased 480 acres (190 hectares) of property to preserve it and to use it for long-term archaeological research.

From 1939 to 1942, the Works Progress Administration employed more than 250 workers to excavate 120,000 square feet (11,000 m2) of the site, which resulted in the recording and processing of 2.3 million archaeological items.

After excavation was temporarily halted during World War II, work resumed in 1945 as part of the Indiana University Archaeology Field School during the summer months.

For thousands of years, the area that was later organized as the eastern United States was home to a succession of native groups who settled near the rivers and used them for travel and trade.

The widespread Mississippian culture, which is named in reference to its geographical origins along the Mississippi River valley and its tributaries, developed around AD 900.

In addition, the Mississippian culture is known for its earthen mounds, designed in shapes including platform, conical, and ridgetop (as also seen at the largest center, Cahokia in present-day southern Illinois).

Working with a variety of soils to create a stable mass, the Mississippian people built major earthworks at the Angel site.

In addition to the mounds, the Mississippians constructed structures and a defensive palisade (stockade) made of wattle and daub with 12-foot (3.7 m) walls and punctuated with bastions.

Scholars believe the town may have had as many as 1,000 inhabitants at its peak, which Indiana archeologist Glenn Albert Black estimated to be about 200 households.

Scholars have speculated that it was potentially due to environmental factors, such as an extended regional drought that reduced the maize (corn) surpluses, and resulted in increasingly scarce natural resources that had once enabled the concentration of population.

Archaeologists also theorize that with the collapse of the Angel chiefdom by AD 1450, many of the site's inhabitants relocated downriver to the confluence of the Ohio and Wabash rivers.

In the eighteenth and nineteenth centuries, groups of other native peoples, such as the Shawnee, the Miami, and other historical tribes moved into the Ohio River valley from the east over the next 150 years.

[18] Although individuals had been surveying the area and digging at the Angel site prior to the beginning of its official excavation in 1939, the archaeological findings were not properly documented.

[19] In 1938, the Indiana Historical Society purchased 480 acres (190 hectares) of property from the Angel family descendants and others to protect the archaeological site from destruction.

[14][22] Excavation was temporarily halted during World War II, but resumed in 1945 as part of the Indiana University Archaeology Field School during the summer months.

[14][26] This project, which extended the work begun by the University of Oxford's Research Laboratory for Archaeology and the History of Art, was one of the "first comprehensive tests in the Americas" to assess the instrument's potential on a New World site.

[14][23] The site's original purchase was later augmented by Elda Clayton Herts's donation of 20 acres (8.1 hectares) containing an early Woodland period mound.

The site occupies more than 600 acres (240 hectares) of land and includes an interpretive center (opened to the public in 1972), recreations of Mississippian structures, and a replica of a 1939 WPA archaeology laboratory.

Archaeological excavations at Angel Mounds State Historic Site continue through Indiana University's field school.

The channel and slough, which existed during the time that the archaeological site was inhabited, created a quiet backwater that surrounded the town on the north, east, and west sides.

The slough and channel to the Ohio River provided easy transit for canoes, as well as a source for freshwater fishing, potable water, and bathing.

Annual spring floods regularly replenished the nutrients in the soil and allowed cultivation of crops that included maize (corn), beans, and squash.

The fertile soil enabled production of surplus crops, which the Mississippian people used for trade and to support a higher density population that developed artisan and craft specialties such as pottery.

[40] Laborers carried 67,785 cubic yards (51,825 m3) of dirt in baskets from the chute (a waterway along the south side of the town) to create the mound.

Based on reports from early European explorers in the southeastern United States who encountered active Mississippian culture villages, this mound was likely the residence of the hereditary chief of the town and the surrounding communities.

Due to the amount of historic period soil disturbance on the summit it is unclear if any structures sat atop this phase.

[14][51] One of the most significant artifacts uncovered at the Angel site was a carved Mississippian culture stone statue of a seated man, which was found at Mound F in November 1940.

[54] Based on research and artifacts discovered at the Angel site, it is believed that the Mississippians used bone fishhooks and nets made of cord to catch mollusks and freshwater fish (catfish and drumfish).