Also a Jeffersonian coinage. A fellow-state.

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1798.  This commonwealth does therefore call on its co-States for an expression of their sentiments…. The rights and liberties of their co-States will be exposed to no dangers.—Thomas Jefferson, Resolutions relative to the Alien and Sedition laws: ‘Works,’ ix. 471 (1859).

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1841.  There is meaning in those words, “Empire State,” when used among co-estates, more than meets the ear.—John Q. Adams in the House of Repr., Sept. 4: Cong. Globe, p. 433, App.

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