Section 4(f) of the Department of Transportation Act of 1966 requires transportation agencies to avoid harming historic places when constructing roads unless there is no "feasible and prudent" alternative to doing so. If a historic place is to be compromised, Section 4(f) requires that the road project include "all possible planning" to minimize the damage. Section 4(f) is the strongest federal preservation law on the book.
Section 4(f) has saved New Orlean's French Quarter from having an elevated freeway built through it and kept a proposed highway widening from destroying portions of the Flathead Indian Reservation in Montana. In Connecticut the proposed Route 11 expansion included a draft Environmental Impact Statement and Section 4(f) evaluation.
For more on Section 4(f) of the Department of Transportation Act of 1966 click on the links below.