Advances in American bottom prehistory: Illinois transportation archaeology two decades after I-270

In 1956 the Illinois Department of Transportation (IDOT) issued its first directive indicating to its engineers that "ruins having historical value should not be needlessly destroyed. " Fifty years later IDOT's cultural resources program continues to be one of the best in the nation. In this article we detail the history of IDOT's cultural resources efforts and focus on its role in carrying out one of the premier CRM projects in the Eastern Woodlands - The FAI-270 Archaeological Mitigation Project. We especially stress the ongoing nature of IDOT's archaeological program and its importance in expanding our knowledge of American Bottom prehistory. Twenty-two years ago, the University of Illinois Press published American Bottom Archaeology: A Summary of the FAI-270 Project Contribution to the Cultural History of the Mississippi River Valley, edited by Charles J. Bareis and James W. Porter (1984)-a volume that quickly became the premier exemplar of the research potential of modern cultural resource management projects in the Eastern Woodlands. The 1984 summary volume was the product of a whirlwind of archaeological activity in the American Bottom concentrated primarily within a fouryear period between 1978 and 1981. The FAI-270 Archaeological Mitigation Project (1-270 Project) was the result of a massive construction program by the Illinois Department of Transportation (IDOT) designed to provide an interstate bypass around St. Louis to the east in the archaeologically rich floodplain of the American Bottom. The accompanying archaeological mitigation project synthesized data from 10,860 excavated features from 98 tested or totally mitigated sites. Lauded by such Eastern Woodland luminaries as James B. Griffin, James Stoltman, Stephen Williams, and others, the American Bottom summary volume was widely adopted as a textbook, and the American Bottom sequence became a comparative benchmark for researchers in many other areas. In the minds of some, the 1984 summary volume became ingrained in the literature as the "final word" on the archaeology of the American Bottom. This is, however, far from the truth; American Bottom archaeological research did not suddenly cease in 1981 when the crews of the initial FAI-270 corridor left the field. Even as the summary volume was being published in 1984, surveys and excavations on transportation-related projects extending the 1-270 corridor to the north were being initiated. The work to the north was again extended in 1990 and again in 1994, and the work is ongoing today as it moves out of the American Bottom floodplain, across the terraces, and into the adjacent dissected uplands. This subsequent research has investigated an additional 118 sites and led to the mitigation of an additional 4,356 features. Initiated by field surveys in 1975, the ultimate scope of what became known colloquially as the 1-270 Project, conducted under the auspices of the Illinois Archaeological Survey (IAS) with the prime contractor being the University of Illinois at Urbana-Champaign (UIUC), was unforeseen. It is clear from early documents that the participants in those planning sessions conceived of the project as having a duration of no more than a year or two of fieldwork followed by a similar period for analysis. They were mistaken. Three decades later, this continuing project has to date, because of the three additional highway extensions to the north, more than doubled in magnitude to a corridor over 77 km in length. It has provided a north-south transect across the archaeologically complex American Bottom and into the bordering uplands. Corridor survey and testing has been continuous since 1975. Comprehensive site excavations have been under way since 1978 with the exception of 1986 and a three-year gap from 1995 to 1998. The original 1-270 Project (later renamed by IDOT as 1-255) began at the point where the Jefferson Barracks Bridge crosses the Mississippi River and ran north to join existing 1-55 just east of Cahokia Mounds State Historic Site (Figure 1). …