23 U.S.C. § 156: Proceeds from the sale or lease of real property

(a) Minimum Charge.—Subject to section 142(f), a State shall charge, at a minimum, fair market value for the sale, use, lease, or lease renewal (other than for utility use and occupancy or for a transportation project eligible for assistance under this title) of real property acquired with Federal assistance made available from the Highway Trust Fund (other than the Mass Transit Account). (b) Exceptions.—The Secretary may grant an exception to the requirement of subsection (a) for a social, environmental, or economic purpose. (c) Use of Federal Share of Income.—The Federal share of net income from the revenues obtained by a State under subsection (a) shall be used by the State for projects eligible under this title.