Chatham is a village in Sangamon County, Illinois, United States. The population was 11,500 as of the 2010 census. The village lies along the original alignment of historic U.S. Route 66 (Illinois Route 4).
Chatham is part of the Springfield, Illinois Metropolitan Statistical Area.
Chatham is located at 39°40′22″N 89°41′54″W / 39.67278°N 89.69833°W / 39.67278; -89.69833 (39.672899, -89.698385).