Oglesby is a city in LaSalle County, Illinois, United States. The population was 3,712 at the 2020 census, down from 3,791 at the 2010 census. It is part of the Ottawa Micropolitan Statistical Area. History Oglesby was a center for mining coal, limestone, and silica, located near the confluence of the Illinois River and the north-flowing Vermilion River. Oglesby grew from an amalgamation of several mining villages, such as Kenosha, Portland, and Black Hollow. It was originally called Portland, due to the cement mined and manufactured in the area that was similar to Portland Cement from England. It was renamed in 1913 after the coal company and in honor of Richard J. Oglesby (1824–1899), a former U.S. Senator and three-time Governor of Illinois. During the Civil War, the Kenosha Coal Company sank a coal mining shaft at Oglesby in 1865. Thatcher Tucker Bent purchased the mine and mineral rights as the Oglesby Coal Company. The mine was innovative and the Bents were very involved in the development of the community. Mrs. Josephine Bent even organized English classes for the immigrant miner's wives. The Marquette Cement Company mined limestone and claimed that the Bent's mine was causing collapses. The conflict eventually liquidated the Oglesby Coal Company, with the Bent selling the machinery to Marquette and auctioning off the farm animals. The Black Hollow Mine was dug in the 1890s as a slope mine along the Vermilion River. It provided coal to its owners, the Illinois Zinc Company in Peru, Illinois. The surface ground layers around Oglesby had excellent exposed limestone and coal; Oglesby also had adequate riverine transport. It soon became an important center for cement manufacture. Before open-pit mining there were several subsurface cement mines: Illinois Clay Products Mine, 1913–1924 Reynolds Clay Mine Marquette Cement Mine As well as several coal mines: Jones Mine, 1865–1930 Oglesby Mine, 1865–1919 Deer Park Mine, 1900–1920 Black Hollow Mine, circa 1890s State parks Matthiessen State Park and Starved Rock State Park are located a few miles east on Illinois State Route 178. With over two million visitors a year, Starved Rock is the most visited of any Illinois state park. Geography Oglesby is located at (41.296762, -89.066074). According to the 2010 census, Oglesby has a total area of , all land. Demographics As of the census of 2020, there were 3,712 people, 1,522 households, and 1,035 families residing in the city. The population density