Swansea is a village in St. Clair County, Illinois, United States. The population was 10,579 at the 2000 census.
In the late 19th century the area that is now Swansea was a mix of farming and commerce. It was home to underground coal mines, foundries, brickyards, and the Gundlach Drill Works, manufacturers of the most efficient grain drills of that era. The early residents were fiercely independent and bent on conducting their own affairs. When the municipality that sat on their doorstep reached out to annex their lands and businesses they decided to start their own community.
On November 27, 1886 a group of 35 area residents petitioned the county government "that they are desirous of having said territory organized as a village...That the name of the proposed village shall be New Swansea."