(a) Transportation systems acquired in whole or in part after 1936 and before 1951—(1) In general. Except as provided in subparagraph (2) of this paragraph, all service performed in the employ of a State or political subdivision thereof in connection with its operation of a public transportation system constitutes covered transportation service if any part of the transportation system was acquired from private ownership after 1936 and before 1951. For purposes of this subparagraph, it is immaterial whether any part of the transportation system was acquired before 1937 or after 1950, whether the employee was hired before, during, or after 1950, or whether the employee had been employed by the employer from whom the State or political subdivision acquired its transportation system or any part thereof.

(2) General retirement system protected by State constitution. Except as provided in paragraph (a)(3) of this section, service performed in the employ of a State or political subdivision in connection with its operation of a public transportation system acquired in whole or in part from private ownership after 1936 and before 1951 does not constitute covered transportation service, if substantially all service in connection with the operation of the transportation system was, on December 31, 1950, covered under a general retirement system providing benefits which are protected from diminution or impairment under the State constitution by reason of an express provision, dealing specifically with retirement systems established by the State or political subdivisions of the State, which forbids such diminution or impairment.

(3) Additions to certain transportation systems by acquisition after 1950. This subparagraph is applicable only in case of an acquisition after 1950 from private ownership of an addition to an existing public transportation system which was acquired in whole or in part by a State or political subdivision thereof from private ownership after 1936 and before 1951 and then only in case service for such existing transportation system did not constitute covered transportation service by reason of the provisions of subparagraph (2) of this paragraph. Service in connection with the operation of such transportation system (including any additions acquired after 1950) constitutes covered transportation service commencing with the first day of the third calendar quarter following the calendar quarter in which the addition to the existing transportation system was acquired, if such service is performed by an employee who became an employee of the State or political subdivision in connection with and at the time of its acquisition from private ownership of such addition and who before the acquisition of such addition rendered service in employment in connection with the operation of the addition so acquired by such State or political subdivision. However, service performed by such employee in connection with the operation of the transportation system does not constitute covered transportation service if, on the first day of the third calendar quarter following the calendar quarter in which the addition was acquired, such service is covered by a general retirement system which does not, with respect to such employee, contain special provisions applicable only to employees who became employees of the State or political subdivision in connection with and at the time of its acquisition of such addition.

(b) Transportation systems in operation on December 31, 1950, no part of which was acquired after 1936 and before 1951—(1) In general. Except as provided in paragraph (b)(2) of this section, no service performed in the employ of a State or a political subdivision thereof in connection with its operation of a public transportation system constitutes covered transportation service if no part of such transportation system operated by the State or political subdivision on December 31, 1950, was acquired from private ownership after 1936 and before 1951.

(2) Additions acquired after 1950. This subparagraph is applicable only in case of an acquisition after 1950 from private ownership of an addition to an existing public transportation system which was operated by a State or political subdivision on December 31, 1950, but no part of which was acquired from private ownership after 1936 and before 1951. Service in connection with the operation of such transportation system (including any additions acquired after 1950) constitutes covered transportation service commencing with the first day of the third calendar quarter following the calendar quarter in which the addition to the existing transportation system was acquired, if such service is performed by an employee who became an employee of the State or political subdivision in connection with and at the time of its acquisition from private ownership of such addition and who before the acquisition of such addition rendered service in employment in connection with the operation of the addition so acquired by such State or political subdivision. However, service performed by such employee in connection with the operation of the transportation system does not constitute covered transportation service if, on the first day of the third calendar quarter following the calendar quarter in which the addition was acquired, such service is covered by a general retirement system which does not, with respect to such employee, contain special provisions applicable only to employees who became employees of the State or political subdivision in connection with and at the time of its acquisition of such addition.

(c) Transportation systems acquired after 1950. All service performed in the employ of a State or political subdivision thereof in connection with its operation of a public transportation system constitutes covered transportation service if the transportation system was not operated by the State or political subdivision before 1951 and, at the time of its first acquisition after 1950 from private ownership of any part of its transportation system, the State or political subdivision did not have a general retirement system covering substantially all service performed in connection with the operation of the transportation system.

(d) Definitions. For purposes of this section:

(1) The term “general retirement system” means any pension, annuity, retirement, or similar fund or system established by a State or by a political subdivision thereof for employees of the State, political subdivision, or both; but such term does not include such a fund or system which covers only service performed in positions connected with the operation of its public transportation system.

(2) A transportation system or a part thereof is considered to have been acquired by a State or political subdivision from private ownership if prior to the acquisition service performed by the employees in connection with the operation of the system or an acquired part thereof constituted employment under the act or under subchapter A of chapter 9 of the Internal Revenue Code of 1939 or was covered by an agreement entered into pursuant to section 218 of the Social Security Act (42 U.S.C. 418), and some of such employees became employees of the State or political subdivision in connection with and at the time of such acquisition.

(3) The term “political subdivision” includes an instrumentality of a State, of one or more political subdivisions of a State, or of a State and one or more of its political subdivisions.

(4) The term “employment” includes service covered by an agreement entered into pursuant to section 218 of the Social Security Act.