U.S. Sens. Dick Durbin and Mark Kirk say the New Philadelphia archaeological site in western Illinois has “exceptional historical significance.”
They say designating it as part of the national park system would ensure the area is protected.
New Philadelphia was plotted in 1836 as the first fully racially integrated community before the Civil War.
Durbin and Kirk say architectural features such as foundations, cellars and wells remain but are threatened by agricultural activity.
Last week the senators sent a letter to the Senate Energy and Natural Resources Committee asking to advance legislation that would authorize a study of the site.