29 U.S. Code § 633 - Federal-State relationship
Nothing in this chapter shall affect the jurisdiction of any agency of any State performing like functions with regard to discriminatory employment practices on account of age except that upon commencement of action under this chapter such action shall supersede any State action.
In the case of an alleged unlawful practice occurring in a State which has a law prohibiting discrimination in employment because of age and establishing or authorizing a State authority to grant or seek relief from such discriminatory practice, no suit may be brought under section 626 of this title before the expiration of sixty days after proceedings have been commenced under the State law, unless such proceedings have been earlier terminated:
Functions vested by this section in Secretary of Labor or Civil Service Commission transferred to Equal Employment Opportunity Commission by Reorg. Plan No. 1 of 1978, § 2, 43 F.R. 19807,92 Stat. 3781, set out in the Appendix to Title 5, Government Organization and Employees, effective Jan. 1, 1979, as provided by section 1–101 of Ex. Ord. No. 12106, Dec. 28, 1978, 44 F.R. 1053.