During the Great Depression, many Puerto Ricans either emigrated to the mainland United States (mainly to the northeastern coast area) or joined the armed forces, with the hope of improving their economic situation.

At the outbreak of World War II, Estrada joined and served in the United States Army.

Being away from his homeland for the first time in his life would in the future serve him as inspiration when composing the bolero "En mi viejo San Juan".

[1] It is Estrada's most popular composition, and is considered a second national anthem by many Puerto Ricans, especially those who live abroad.

San Juan and the town of Isabela have honored Estrada's memory by naming streets and a school after him.