The Lewisville Site is located in southern Denton County. It was formerly on the west side of the Elm Fork of the Trinity River at the mouth of Hickory Creek, but it was inundated by Lake Lewisville in April 1957. During periods of drought from 1978 through 1980 the site was exposed for the first time since 1957. It had been found in 1951 during the collection of Pleistocene vertebrate remains from a borrow pit used for construction of Lewisville Lake. An area of baked clay near the remains of an immature extinct bison was observed by the late Theodore E. White of the National Park Service and Glen L. Evans of the Texas Memorial Museum. With Edward B. Jelks of Southern Methodist University, who was conducting archeological examinations in the project area, Evans and White concluded that the baked area was a natural, not a cultural, phenomenon. Subsequent examinations of the borrow area by members of the Dallas County Archeological Society at Jelks's suggestion resulted in the area becoming known as the Lewisville Archeological Site (41DN72). Later publication of the results of examinations elevated the Lewisville Site into a national-level controversy among prehistorians.
The earlier investigations between 1951 and 1957, but most extensively in 1956–57, indicated that the site contained partial remains of some thirty faunal species (extinct and modern) associated with, or in close proximity to, twenty-one areas of baked clay that were called "fire-hearths." The faunal remains represented primarily mammoths, horses, camels, bison, wolves, coyotes, prairie dogs, peccaries, glyptodons, raccoons, deer, antelope, mussels, snakes, short-faced bears, lizards, fish, birds, tortoises, rabbits, squirrels, packrats, skunks, and mud-daubers. Hackberry seeds were found. The baked-clay areas were of two basic forms, ranging from small (57 by 67 centimeter) ovals, some nine centimeters in depth, to large (90 by 103 centimeter) roughly elliptical areas of overlapping hearths up to forty-five centimeters in depth. Seven artifacts were found, but only one provided evidence of distinctive cultural association. A Clovis point thought to belong to a people known to be nomadic hunters of big game was the only artifact found in situ in one of the "hearths" (No. 1). The spearpoint became a focus of controversy second only to the subsequent carbon-14 dates. The other six artifacts, a chopper, a hammerstone, three unaltered flakes, and a broken flake knife, had been found eroding out in the floor of the borrow pit.
Radiocarbon dates obtained by several different laboratories over a period of several years confirmed W. W. Crook, Jr., and R. D. Harris's initial reported date for the site in excess of 37,000 B.P. Between 1957 and 1963 the site was widely debated. Controversy centered on the age, cultural affinity, and whether the "site" was the result of natural or human activity. Subsequent to a critical review of Man's Antiquity in North America by J. A. Graham and R. F. Heizer (1967), the site was essentially shelved academically. After it was inundated, resolution of the Lewisville enigma was not considered likely, even by Crook and Harris.
The investigations of 1978–80 directed by Dennis Stanford of the Smithsonian Institution and Robert J. Burton and Larry Banks from the United States Army Corps of Engineers produced some new data that essentially parallel those of Crook and Harris, but that have also provided the basis for a more refined interpretation of the site. The new interpretations are possible primarily because of advancements in analytical techniques and procedures developed since the 1950s. Indications are that the Lewisville Site represented a possible specialized site of Clovis-aged (ca. 12,000 B.P.) people who were using fires at least partially fueled by lignite. The Cretaceous-age lignite was responsible for producing the earlier and erroneous dates. Because of this contamination, however, later attempts to obtain absolute dates for the site were unsuccessful, though it seems to represent the Western Hemisphere's oldest culture. The entire collection of materials from the site is located at the Smithsonian Institution.