Congress on Friday sent the defense bill to President Barack Obama. Sens. Dick Durbin and Mark Kirk say the bill includes a provision directing the Secretary of the Interior to conduct a study on the site.
New Philadelphia was plotted in 1836 as the first fully racially integrated community before the Civil War. It is the site of the first town founded and built by a freed slave before the Civil War.
The senators say designating it as part of the national park system would ensure the area is protected. The senators say agricultural activity threatens some of the site's architectural features.