Initially established by Congress in the early 20th century and authorized in their current form in 1955, there are active SDFs in 19 states and Puerto Rico as of February 2024.

With most of the PRNG being activated and mobilized during World War II, a secondary force was proposed to deal with the area of Puerto Rico.

[2] In April 1942, the colonial legislature passed Law 28, which approved the creation of a new militia-based program to fill the role of the soldiers that had left.

[4] The State Guard tried to promote itself in the media, publishing a government-sponsored magazine named Centinela Alerta and a column in the newspaper El Mundo.

[5] Colonial governor and Gen. Esteves awarded a certificate to all the enlisted men, while those who served at least three years were also given a medal approved by the legislature.

[5] The modern PRSG was reformed in 1976 following the approval of the Military Law of Puerto Rico it's considered the state controlled branch of the PRNG.

This group was formed to provide Puerto Rico a trained and organized military force in the event of a state security emergency or if the National Guard is deployed.

The PRSG comprises retired, activewith , and reserve military personnel and selected professional persons who volunteer their time and talents in further service to their state.

With the approved resources, the PRSG is able to recruit and train personnel to provide security and defense with the armories, as well as to assist civilian authorities in cases of natural disasters, emergencies, and serious disturbances of public order.

In the PRSG, there is a large representation of veterans with extensive combat and command experience as well as non-priors with significant professional and paramilitary backgrounds which greatly enhances the organization.

The PRSG has been a very active force multiplier for the PRNG, supporting Federal mobilizations (legal and medical support), and its current mission is to assist the National Guard especially in concern to homeland security and SAR duties (natural disasters, civil disturbances, communities service and facilities management).

The PRSG comprises retired, active and reserve military personnel and selected professional persons who volunteer their time and talents in further service to their state.

All PRSG appointments, commissions, warrants, and enlistments are recognized and authorized by the Governor of Puerto Rico through the Adjutant General of PR.

This major command was formed to provide Puerto Rico with a trained and organized military force in the event of a state security emergency or if the National Guard is deployed.

The PRSG comprises retired, active and reserve military personnel and selected professional persons who volunteer their time and talents in further service to their state.