The law of Eminent Domain is in flux. The Constitution , Article 5th Amendment, states plainly that no private property shall be taken without just compensation and for a public use. Several cases have held all the way up to the Supreme Court of the United States that a municipality may take private property in order to implement a plan of urban development so that a section of town might be developed to produce more commerce or supply an attractive betterment to the community.
The spirit of these cases tends to present the phrase "public purpose" as synonymous with "public use". This is far away from the framers intent in the law and happily, the pendulum is swinging back to the original meaning of "public use". Recently, these stretched linguistic understandings have been curtailed and the gist of the law is sliding back to the "public use" as originally envisioned. Now, only roads and bridges, forts and police stations can be good enough reasons for the government to take your land and offer you fair value compensation. There is much we can do to protect an individual who does not wish to sell to a municipality which sees your land as "necessary" to its plan.