About Saint Petersburg, Pennsylvania
   St. Petersburg is located in western Clarion County at 41°09′39″N 79°39′14″W.  Pennsylvania Route 58 passes through the borough, leading 2 miles (3 km) southwest to Foxburg on the Allegheny River and east 7 miles (11 km) to Callensburg on the Clarion River. Pennsylvania Route 478 leads northwest 2 miles (3 km) to Interstate 80 east of Emlenton.
 
   According to the United States Census Bureau, St. Petersburg has a total area of 0.32 square miles (0.83 km2), all of it land.
 
As of the censu of 2000, there were 405 people, 164 households, and 115 families residing in the borough.