1987—Subsec. (a). Pub. L. 100–17 amended subsec. (a) generally. Prior to amendment, subsec. (a) read as follows: “If a Federal project cannot proceed to actual construction because comparable replacement sale or rental housing is not available, and the head of the Federal agency determines that such housing cannot otherwise be made available he may take such action as is necessary or appropriate to provide such housing by use of funds authorized for such project.”

Subsec. (b). Pub. L. 100–17 amended subsec. (b) generally. Prior to amendment, subsec. (b) read as follows: “No person shall be required to move from his dwelling on or after January 2, 1971, on account of any Federal project, unless the Federal agency head is satisfied that replacement housing, in accordance with section 4625 (c)(3) of this title, is available to such person.”

Amendment by Pub. L. 100–17 effective on effective date provided in regulations promulgated under section 4633 of this title (as amended by section 412 of Pub. L. 100–17), but not later than 2 years after Apr. 2, 1987, see section 418 of Pub. L. 100–17, set out as a note under section 4601 of this title.