San Antonio Could Soon Overtake Philadelphia as the Nation’s 6th Largest City

San Antonio has spent years growing steadily while much of the national attention around Texas stayed focused on Austin, Dallas, or Houston.

Now, the city is approaching a milestone that says a lot about how much it has changed over the last decade: San Antonio is getting closer to overtaking Philadelphia as the sixth-largest city in the United States.

According to U.S. Census Bureau estimates, Philadelphia’s population stood at roughly 1,574,281 residents as of July 2025, while San Antonio reached an estimated 1,548,422 residents. That leaves a gap of about 26,000 people between the two cities, a dramatic shift from 2020, when Philadelphia had roughly 162,000 more residents than San Antonio.

The growth itself isn’t entirely surprising to people living here.

San Antonio has been steadily expanding for years as more families, workers, and businesses relocate across the South in search of affordability, job opportunities, and lower costs of living compared with many larger metropolitan areas. But the conversation around the rankings also highlights something more specific about how San Antonio has grown.

Part of the city’s rapid population increase comes from annexation, the expansion of city boundaries to incorporate additional land and surrounding communities. Unlike many older Northeastern cities whose borders have remained fixed for generations, Southern cities like San Antonio have historically had more flexibility to grow outward geographically.

Katie Martin, who leads research at The Pew Charitable Trusts’ Philadelphia research initiative, told The Philadelphia Inquirer that expanding city boundaries naturally increases population totals over time.

“They’re increasing the square footage of the city over time, which does increase, often, the population,” Martin said. “Whereas, Philadelphia, we have been the city we have been for 150 years.”

Still, annexation alone doesn’t fully explain San Antonio’s growth trajectory.

The city has also become increasingly attractive to out-of-state movers, including younger families, military families, remote workers, and people looking for more affordable housing options compared with other major Texas cities. And population growth changes how cities are perceived politically, economically, and culturally.

Population rankings can influence federal funding, political representation, and how resources are distributed at both the state and national levels. The symbolic significance matters too. Moving into the sixth-largest city position would further solidify San Antonio as one of the country’s major urban centers. 

The city is no longer growing quietly. National attention is catching up, businesses are investing more, and projects tied to downtown development, sports infrastructure, and tourism continue to reshape San Antonio. 

Whether San Antonio officially overtakes Philadelphia in the ranking in the next few years or not, the larger shift is already happening.