First, the interstate system was not constructed by the federal government, but by the individual states, using 90 percent federal funding. A great deal of the needed land was in fact taken through eminent domain proceedings. This was less common in western states, because so much land in unpopulated areas is owned by the federal government.

Eminent domain "takings" for public improvements such as highways is a centuries-old practice, recognized in the Fifth Amendment to the US Constitution. Procedures vary somewhat from state to state, but in general, if the landowner is not satisfied with the price being offered for the property, he can ask for a judicial proceeding, at which evidence from appraisers will be offered to determine the property's "fair market value."

Incidentally, many states also give eminent domain authority to private companies providing a public service, including electric and gas utilities, railroads, and pipeline companies.