Armstrong, Illinois, is a small, unincorporated community in Middlefork Township, Vermilion County, located in the northwestern part of the county, just northeast of the intersection of U.S. Route 136 and Illinois State Route 49, approximately four miles west of Potomac. Founded in 1876 on land owned by Thomas and Henry Armstrong, the town was established along the route of the Havana, Rantoul, and Eastern narrow-gauge railroad, later integrated into the Illinois Central Railroad. A significant event in its history occurred on October 2, 1908, when a devastating fire destroyed key buildings, including the general store, harness shop, blacksmith shop, lumber yard, opera house, post office, and grain elevator, with residents manually pumping water to combat the blaze due to the absence of fire equipment. Today, Armstrong remains a quiet rural community, served by the Armstrong Township High School, home of the Trojans, and characterized by its proximity to nearby towns like Potomac and Penfield, offering a glimpse into small-town life in central Illinois.

Armstrong currently has 2 single family homes for sale with an average list price of $132,250. The average annual property tax for Armstrong is $2,043.83.