delivered the opinion of the Court.

The dispute in this ease commenced when the Delaware, Lackawanna & Western Railroad Co. and the Erie *170Railroad Co. filed a joint application for approval by the Interstate Commerce Commission of a proposed merger, the surviving company to be known as the Erie-Lackawanna Railroad Co. Supervision by the Commission of railroad mergers is required by § 5 (2) of the Interstate Commerce Act, 54 Stat. 905, 49 U. S. C. § 5 (2), and the statute directs the Commission to authorize such transactions as it finds will be “consistent with the public interest.” The Commission concluded in this case that the public interest would be served by a merger of the two applicants and that finding has not been questioned. The point in issue is whether the conditions attached to the merger for the protection of the employees of the two roads satisfy the congressional mandate embodied in § 5 (2) (f) of the Act, which provides in relevant part that:

“As a condition of its approval, under this paragraph (2), of any transaction involving a carrier or carriers by railroad subject to the provisions of this part, the Commission shall require a fair and equitable arrangement to protect the interests of the railroad employees affected. In its order of approval the Commission shall include terms and conditions providing that during the period of four years from the effective date of such order such transaction will not result in employees of the carrier or carriers by railroad affected by such order being in a worse position with respect to their employment, except that the protection afforded to any employee pursuant to this sentence shall not be required to continue for a longer period, following the effective date of such order, than the period during which such employee was in the employ of such carrier or carriers prior to the effective date of such order.” (Emphasis added.)

*171Before the Commission’s hearing examiner, the railroads suggested that the “New Orleans conditions” be imposed in satisfaction of § 5 (2)(f). These conditions derive their name and substance from the Commission’s decision in the New Orleans Union Passenger Terminal Case, 282 I. C. C. 271, and they provide compensation benefits for employees displaced or discharged as a result of a merger.1 After the hearing had concluded, however, appellant Railway Labor Executives’ Association (RLEA) filed a brief with the examiner claiming that compensatory conditions were not enough since, in its view, the second sentence of § 5 (2) (f) imposes a minimum requirement that no employee be discharged for at least the length of his prior service up to four years following consummation of the merger. The hearing examiner did not agree with the RLEA’s reading of §5 (2) (f) and recommended the New Orleans conditions to the Commission, a recommendation which the Commission unanimously adopted. 312 I. C. C. 185. Appellants then instituted proceedings in the United States District Court of Michigan, seeking to enjoin the Commission’s order approving the merger. A temporary restraining order issued following testimony by a representative of the RLEA that irreparable injury to the employees would otherwise ensue. However, after hearing the case on its merits, the District Court dissolved the restraining order and dismissed appellants’ complaint. 189 F. Supp. *172942. Direct appeal to this Court followed and we noted probable jurisdiction. 365 U. S. 809.

Preliminarily, it.must be noted that the adequacy of the New Orleans conditions is not an issue before this Court: Appellants did not challenge their sufficiency below, nor do they argue the point here.2 Rather, appellants’ sole contention is that no compensation plan is adequate unless it is based on the premise that all the employees currently on the payroll remain in the surviving railroad’s employ for at least the length of their previous employment up to four years. Appellants do not say that every employee must remain in his present job, but they do insist that some job must remain open for each one. We think, however, that a review of the background of § 5 (2) (f) and its subsequent interpretation demonstrates the defects in appellants’ position.

Section 5 (2) (f), as it now appears, was enacted as part of the Transportation Act of 1940. A broad synopsis of the occurrences which led to the enactment of those sections on railroad consolidation of which § 5 (2) (f) is a part is contained in the Appendix to this Court’s opinion in St. Joe Paper Co. v. Atlantic Coast Line R. Co., 347 U. S. 298, 315, and it is unnecessary to reproduce that *173material here except to note that: “The congressional purpose in the sweeping revision of § 5 of the Interstate Commerce Act in 1940, enacting § 5 (2) (a) in its present form, was to facilitate merger and consolidation in the national transportation system.” County of Marin v. United States, 356 U. S. 412, 416. The relevant events, for present purposes, date from 1933, when Congress passed the Emergency Railroad Transportation Act, 48 Stat. 211. That Act contemplated extensive railroad consolidations and provided for employee protection pursuant thereto in the following language:

“[N]or shall any employee in such service be deprived of employment such as he had during said month of May or be in a worse position with respect to his compensation for such employment, by reason of any action taken pursuant to the authority conferred by this title.”

Shortly before the Emergency Act expired in 1936, a great majority of the Nation’s railroads and brotherhoods entered into the Washington Job Protection Agreement,3 an industry-wide collective bargaining agreement which also specified conditions for the protection of employees in the event of mergers. Unlike the Emergency Act, however, the Washington Agreement provided for compensatory protection rather than the “job freeze” previously prescribed. Subsequently, efforts commenced to re-evaluate the law relating to railroad consolidations and a “Committee of Six” was appointed by the President to study the matter. Those portions of the Committee’s final report pertaining to employee protection urged codification of the Washington Agreement4 and a bill drafted *174along those lines, S. 2009, was passed by the Senate in 1939. 84 Cong. Rec. 6158. The Senate bill contained language identical to that now found in the first sentence of § 5 (2) (f) — i. e., the transaction should contain “fair and equitable” conditions.

A bill similar in this respect to S. 2009 was introduced in the House but, before it was sent to the Conference Committee, Representative Harrington inserted an amendment which added a second sentence to the one contained in the original version, this sentence stating that:

“[N]o such transaction shall be approved by the Commission if such transaction will result in unemployment or displacement of employees of the carrier or carriers, or in the impairment of existing employment rights of said employees.” 84 Cong. Rec. 9882.

The bill came out of the Conference Committee without Representative Harrington’s addendum and, dissatisfaction having been expressed by Representative Harrington and others, a motion to recommit was passed by the House. This motion required that the language of the original House bill be restored “but modified so that the sentence in section 8 which contains the provision known as the Harrington amendment” should speak as the second sentence of § 5 (2)(f) now does — viz., “[the] transaction will not result in employees of said carrier . . . being in a worse position with regard to their employment.” 86 Cong. Rec. 5886. This new phraseology was adopted by the Conference Committee, with the added limitation that such protection need extend no more than four years, and the bill passed without further relevant alteration. 86 Cong. Rec. 10193, 11766.

It would not be productive to relate in detail the various statements offered by members of the House to explain the significance of the events outlined above. It is enough to say that they were many, sometimes ambig*175uous and often conflicting. However, certain points can be made with confidence. First, it is clear that there were two alterations made in the substance of the original Harrington amendment: Not only was a four-year limitation imposed, but also general language of imprecise import was used in substitution for language clearly requiring “job freeze” such as appeared in the original amendment and the 1933 Act.5 Secondly, the representatives whose floor statements are entitled to the greatest weight are those'House members who had the last word on the bill — the House conferees who explained the final version of the statute to the House at large immediately prior to passage — rather than those Congressmen whose voices were heard in the early skirmishing but who did not participate in the final compromise.6 Finally, although *176it might be an overstatement to claim that their remarks are dispositive, the statements the House conferees gave in explanation of the final version clearly reveal an understanding that compensation, not “job freeze,” was contemplated.7 Appellants vigorously argue that the legislative history of § 5 (2) (f) supports their interpretation. However, were we to agree, it would be necessary to say that a substantial change in phraseology was made for no purpose and to disregard the statements of those *177House members most intimately connected with the final version of the statute.

The indications gleaned from the history of the statute are reinforced and confirmed by subsequent events. Immediately after the section was passed, interested parties — including the brotherhood appealing in this case — expressed the opinion that compensation protection for discharged employees was the intendment of § 5 (2)(f).8 The Commission echoed this interpretation in its next annual report, I. C. C. 55th Ann. Rep. 60-61, and began imposing compensatory conditions, and only compensatory conditions, in proceedings involving § 5 transactions. See, e. g., Cleveland & Pittsburgh R. Co. Purchase, 244 I. C. C. 793 (1941). The Commission has consistently followed this practice to date in over 80 cases, with the full support of the intervening brotherhoods and the RLEA;9 indeed, in one case where a *178variant of the present dispute arose, the RLEA argued at length that § 5 (2) (f) did not impose a mandatory job freeze requirement — compensatory conditions would be satisfactory.10 It is true that many of these prior transactions did not involve consolidations of the magnitude here presented. However, the relevance of this point is unclear since the statute makes no distinctions based on the type of transaction considered, and it is apparent that the underlying principle remains the same whether 100 or 1,000 employees are affected.11

Appellants’ last point is that two cases in this Court have previously treated the present question favorably to their position. Railway Labor Executives’ Assn. v. United States, 339 U. S. 142, and Order of Railroad Telegraphers v. Chicago & North Western R. Co., 362 U. S. 330. However, neither the holding nor the language of these cases, in fact, supports appellants’ claim. The RLEA case was not concerned with the types of protection to be afforded employees for the first four years following the merger; the only question was whether *179compensatory benefits could be extended beyond four years, and the Court held they could. Appellants point to passages in the opinion, 339 U. S., at 151-154, in which, they assert, the Court recognized that only one change— the four-year limitation — was blended into the Harrington amendment between origination and final approval. However, this contention ignores the plain recognition of the Court, revealed on page 152 of the opinion, that two changes occurred, one of which being the alteration in language pertinent to the resolution of this case. The Railroad Telegraphers case is equally inapposite. The question in that case concerned the power of a federal court to enjoin a strike over the railroad’s refusal to bargain concerning a “job freeze” proposal in the collective bargaining contract, and there is no discussion of the present problem in the opinion of the Court.

In short, we are unwilling to overturn a long-standing' administrative interpretation of a statute, acquiesced in by all interested parties for 20 years, when all the signposts of congressional intent, to the extent they are ascertainable, indicate that the administrative interpretation is correct. . Consequently, the judgment of the District Court must be

Affirmed.

dissenting.

This case is a minor episode in an important chapter of modern history. It concerns the impact of economic and technological changes on workers1 and the manner in *180which government will deal with it. The courts do not determine that policy; it is a legislative matter. But the judicial attitude has much to do with the manner in which legislative ambiguities will be resolved.

There are some who think that technological change will produce both our highest industrial and business activity and our greatest unemployment. Dr. Robert M. Hutchins recently stated the basic conflict between individual freedom and technology:

“Individual freedom is associated with doubt, hesitancy, perplexity, trial and error. These technology *181cannot countenance. Liberty under law presupposes the supremacy of politics. It presupposes the possibility, for example, that political deliberation might lead to the decision to postpone the introduction of a new machine. Technology, on the other-hand, asserts that what we can do is worth doing; the things most worth doing are those we can do most efficiently . . . Two Faces of Federalism (1961), p. 22.

The measure of the conflict is seen only in a broad frame of reference. As Dr. Hutchins said:

“Technology holds out the hope that men can actually achieve at last goals toward which they have been struggling since the dawn of history: freedom from want, disease, and drudgery, and the consequent opportunity to lead human lives. But a rich, healthy, workless world peopled by bio-mechanical links is an inhuman world. The prospects of humanity turn upon its ability to find the law that will direct technology to human uses.” Two Faces of Federalism (1961), p. 24.

The Secretary of Labor, Arthur J. Goldberg, recently put the problem in simple terms:2

“The issue being joined in our economy today— one that is present in some form in every major industrial negotiation — is simply stated: how can the necessity for continued increases in productivity, *182based upon labor-saving techniques, be met without causing individual hardship and widespread unemployment?”

This case is a phase of that problem.

This-is not the first instance of a controversy settled in Congress by adoption of ambiguous language and then transferred to the courts, each side claiming a victory in the legislative halls.3

The Senate passed a bill which required the Interstate Commerce Commission in approving a railroad merger to make “a fair and equitable arrangement to protect the interest of the employees affected.”4 The House Committee adopted the same language.5 When the bill reached the floor of the House, Mr. Harrington suggested the following proviso:6

“Provided, however, That no such transaction shall be approved by the Commission if such transaction will result in unemployment or displacement of employees of the carrier or carriers, or in the impairment of existing employment rights of said employees.”

That amendment would have prohibited permanently the displacement of employees as a result of mergers. It was adopted by the House.7 But' in Conference that proviso was eliminated along with the merger provisions that gave rise to it.8 The House recommitted the bill with instructions that the provisions relating to combinations and consolidations of carriers be included in the bill, and be amended to provide that the Commission *183must include in its orders authorizing mergers “terms and conditions providing that such transaction will not result in employees of said . . . carriers being in a worse position with respect to their employment.”9

The Conference accepted this version, limiting the protective clause to four years. The Conference Report emphasizes that the change made in the Harrington proposal was in limiting its operation to four years.10 *184Mr. Lea, Chairman of the House Conferees, stated the same in the House:11

“The substitute that we bring in here provides two additional things. First, there is a limitation on the operation of the Harrington amendment for 4 years from the effective date of the order of the Commission approving the consolidation. In other words, the employees have the protection against unemployment for J¡. years, but the Commission is not required to give them benefits for any longer period. If the employees themselves make an agreement with the railroad company for a better or a longer period, that is a matter between the railroad men and the railroads, but this 4-year limitation is established by the pending conference agreement.

“There is another limitation on the protective benefits afforded by the amendment. The benefit period shall not be required for a longer period than the prior employment of the employee before the consolidation occurred. In other words, under the original Harrington amendment, if a man was employed for 6 months, he would indefinitely be subject to the benefits of the amendment from the railroad company. We have changed that so the railroad company will not be required to maintain him in no worse condition as to his employment for any longer period than he worked before the consolidation occurred.

“We believe that is a very fair and a very liberal provision for labor. We believe that railway labor substantially agrees in that viewpoint. We take nothing from labor by this agreement.” (Italics added.)

*185Mr. Wolverton, another House Conferee, stated:12

“It was recognized that the real intent of the sponsors was to save railroad employees from being suddenly thrust out of employment as the result of any consolidation or merger entered into.” (Italics added.)

These are the statements13 which, the Court says, “are entitled to the greatest weight” in, interpreting the proviso. I do not think that these statements — nor any part of this legislative history — “clearly reveal an understanding that compensation, not ‘job freeze,’ was contemplated.” Instead I find this legislative history — -as the Court elsewhere seems to recognize — to be, at best, ambiguous. Compensatory relief will result in the employees’ bearing the initial shock of the railroads’ reduction in plant. The Commission and the railroads contend for a philosophy of firing first and picking up the social pieces later. The Court seizes on ambiguous materials to impute to Congress approval of that philosophy. I would resolve the ambiguity in favor of the employees. I would read the proviso as meaning that nothing less than four-year employment protection to every employee *186would satisfy the Act, though not necessarily a four-year protection in his old job. In a realistic sense a man without a job is “in a worse position with respect to” his “employment,”' though he receives some compensation for doing nothing. Many men, at least, are not drones; and their continued activity is life itself. The toll which economic and technological changes will make on employees is so great that they, rather than the capital which they have created,14 should be the beneficiaries of any doubts that overhang these legislative controversies when they are shifted to the courts.