Law #1 of August 4, 1952 of the Commonwealth of Puerto Rico establishes a full state holiday on July 25 of every year, to be known as Puerto Rico Constitution Day. Sometimes referred to as Commonwealth Day, the holiday commemorates the day the Constitution of Puerto Rico, approved on July 3, 1952, was signed into law by Governor Luis Munoz Marin the same year.
Up to then, July 25 had been a holiday in Puerto Rico, known as "Occupation Day", to commemorate the arrival of United States military forces on July 25, 1898 in an area of the municipality of Yauco that in the early 20th century would become the separate municipality of Guanica.
The government of Puerto Rico holds a commemorative ceremony every year. It is celebrated with parades, speeches, fireworks, and parties.
The most interesting thing about the relationship between Puerto Rico and the United States is its voluntary nature.