Tacna-Arica Controversy (täk´nə-ərē´kə), 1883–1929, dispute between Chile and Peru. It arose from provisions of the Treaty of Ancón (1883), which ended the War of the Pacific (see Pacific, War of the). Victorious Chile was ceded the southern provinces of Peru, Tacna and Arica, but only for 10 years; a plebiscite was then to determine the ownership. The plebiscite was not held because negotiations between the countries failed. Chile in 1909 began colonizing the two provinces—a course that led in 1911 to a diplomatic break between Peru and Chile, and the United States watched with concern while relations grew worse.

In 1922 representatives of Chile and Peru, meeting in Washington, agreed upon arbitration by the president of the United States. Calvin Coolidge in 1925 sent as plebiscitary commissioner Gen. John J. Pershing, who was replaced (1926) by Gen. William Lassiter. Neither commissioner achieved anything of note, but at the suggestion of Frank B. Kellogg, diplomatic relations between Peru and Chile were resumed in 1928. The next year President Herbert Hoover made a proposal accepted by both Peru and Chile. It provided that Chile should retain Arica but return Tacna to Peru; construct a free port for Peru at Arica, with port and rail installations; transfer all state-owned real estate and buildings in Tacna to Peru; and pay an indemnity of $6 million.

See W. J. Dennis, ed., Documentary History of the Tacna-Arica Dispute (Univ. of Iowa Studies in Social Sciences, 1927, repr. 1971); Tacna and Arica: An Account of the Chile-Peru Boundary Dispute and of the Arbitrations by the United States (1931); J. F. Wilson, The United States, Chile and Peru in the Tacna and Arica Plebiscite (1979).