Petersburg is located close to the center of Illinois. Petersburg is part of Menard County. Petersburg has 1.46 square miles of land area and has no water area. As of 2010-2014, the total Petersburg population is 2,173, which has shrunk 5.48% since 2000. The population growth rate is much lower than the state average rate of 3.62% and is much lower than the national average rate of 11.61%. Petersburg median household income is $43,551 in 2010-2014 and has grown by 25.55% since 2000. The income growth rate is higher than the state average rate of 22.70% and is lower than the national average rate of 27.36%. Petersburg median house value is $101,000 in 2010-2014 and has grown by 24.08% since 2000. The house value growth rate is lower than the state average rate of 34.33% and is much lower than the national average rate of 46.91%. As a reference, the national Consumer Price Index (CPI) inflation rate for the same period is 26.63%. On average, the public school district that covers Petersburg is better than the state average in quality. The Petersburg area code is 217.