Gross income does not include—
(1) income derived from any public utility or the exercise of any essential governmental function and accruing to a State or any political subdivision thereof, or the District of Columbia; or
(2) income accruing to the government of any possession of the United States, or any political subdivision thereof.
(Aug. 16, 1954, ch. 736, 68A Stat. 35; Pub. L. 94–455, title XIX, § 1901(a)(19), Oct. 4, 1976, 90 Stat. 1766.)