The third stamp honored Puerto Rico featuring 'La Fortaleza', the Spanish Governor's Palace.
The stamp's shows a rural Puerto Rican holding a cogwheel for industry and a box representing the election.
The stamp was inspired by a sketch prepared by Irene Delano of the Office of the Governor of Puerto Rico.
The United States issued a 5-cent definitive stamp in Muñoz Marin's honor on February 18, 1990.
[6] San Juan, Puerto Rico was commemorated with an 8-cent stamp on its 450th anniversary issued September 12, 1971.