In the historical center, the city can trace its Barangay Post Proper Southside back nearly a century because the city's foundation has been the establishment of buildings whose use has endured over time. Post Proper Southside has been the fundamental unit of the Philippines. Thus, the barangay was created as the "Barrio" in ancient history as established by the Filipinization movement started in 1902.

The name "Post Proper" in barangay is from an area divided from U.S. military reservation land in times of American occupation period of the Philippines. The barangay evolved from the former residential area that was established by the American colonial administration as part of their civilian government structure.

Throughout the years, our barangay has maintained its residential character while adapting to modern urban development. The community has grown from a small settlement to a thriving neighborhood that balances progress with tradition.

Today, Barangay Post Proper Southside stands as a model community that embraces both its historical roots and its vision for the future, continuing to serve as a vital part of our city's rich heritage.