 Amtrak took over operation of most intercity rail passenger service in the United States on May 1, 1971; up until then such services were run by various private railroads.The private railroads chose to retain their second generation passenger locomotives for freight service, or to operate the various commuter services which, by law, did not pass to Amtrak.To operate these intercity services the company had to buy or lease from the private railroads whatever locomotives remained.