Puerto Rico’s flag was officially adopted by the Commonwealth in 1952.
The flag had originated in 1895 among members of the Puerto Rican Revolutionary Committee in New York, but it was not officially recognized by Puerto Rico’s elected government at that time. After several unsuccessful efforts to formalize it, Governor Luis Muñoz Marín and the Puerto Rican legislature adopted it as the official flag in July 1952, when the Commonwealth of Puerto Rico was established.
The design has five alternating red and white horizontal stripes, a blue triangle at the hoist, and a single white star. Its basic arrangement was inspired by the Cuban flag, with the colors and layout reversed. The 1952 law identified red, white and blue but did not specify the exact shade of blue.
A later regulation issued on 3 August 1995 restated the flag’s status and helped establish medium blue as the common modern shade. That later date can cause confusion, but 1952 is the key adoption year asked for here: it marks the Commonwealth’s formal recognition of the flag.