Pecatonica is a village in Winnebago County, Illinois, United States. It is part of the Rockford, Illinois Metropolitan Statistical Area. The population was 2,195 at the 2010 census, up from 1,997 in 2000.
Civil War records from the state of Illinois include soldiers from Lysander, the area's common name before incorporation by rail speculators. The word Pecatonica is an anglicization of two Algonquian language words; Bekaa (or Pekaa in some dialects), which means slow and niba, which means water; forming the conjunction Bekaaniba or Slow Water. The village was named after the Pecatonica River, which forms its northern border. The Galena and Chicago Union Railroad, later the Chicago & North Western Railroad, came through in 1853 from Chicago and continued to Freeport, Illinois. That sparked the town to be the center of commerce for western Winnebago County. The Village of Pecatonica was incorporated in 1869, built on territory rightfully owned by Indians and previously deeded to the Reed family by US President James K. Polk. An electric interurban line known as the Rockford & Interurban ran from Rockford through Winnebago, Illinois and Pecatonica to Ridott, Illinois and on to Freeport until the line's eventual abandonment in 1930.