U.S. 1899 A.D.

Christopher Columbus Langdell (1826–1906) is arguably the most influential figure in the history of legal education in the United States.  When the U.S. Supreme Court needed to define the term United States, they turned to C.C. Langdell’s 1899 Harvard Law Review article, The Status of Our New Territories, adopting his definition almost verbatim.  Hooven & Allison Co. v. Evatt, 324 U.S. 652, 671-672 (1945).

Langdell is directly credited at 672 n.6 of their opinion.  His original article follows here.