Petersburg, IL -- U.S. city in Illinois Population (2000): 2299 Housing Units (2000): 1076 Land area (2000): 1.347870 sq. miles (3.490967 sq. km) Water area (2000): 0.000000 sq. miles (0.000000 sq. km) Total area (2000): 1.347870 sq. miles (3.490967 sq. km) FIPS code: 59312 Located within: Illinois (IL), FIPS 17 Location: 40.011503 N, 89.851505 W ZIP Codes (1990): Note: some ZIP codes may be omitted esp. for suburbs. Headwords: Petersburg, IL Petersburg