Zamboanga del Sur Day, or Araw ng Zamboanga del Sur, is observed in the Philippine province of Zamboanga del Sur every September 17. This special non-working holiday commemorates the anniversary of the province's creation, which was officially established when it was divided from Zamboanga del Norte in 1952. The celebration has taken place annually since 1953 and has been associated with the Megayon Festival since 2011, a name meaning "unity" in the language of the Subanen people. The festival highlights the diverse ethnic and religious groups residing in Zamboanga del Sur, promoting harmony among them. Historically, the region has a rich cultural background, having been home to indigenous groups such as the Subanen and Maguindanaon, and it played a significant role during the Spanish colonization and the Philippine Revolution.