Plaque honoring 2,486 Macon County soldiers that fought in the War of the Rebellion, 1861-65
According to the US Census Bureau, the county has a total area of 586 square miles (1,520 km2), of which 581 square miles (1,500 km2) is land and 5.2 square miles (13 km2) (0.9%) is water.[4]
Macon County is primarily flat, as is most of the state and all of the surrounding counties, the result of geological activity during the Pleistocene epoch. During the Illinoian Stage of the Pleistocene, the Laurentide Ice Sheet covered about 85 percent of Illinois, including the Macon County area. The subsequent thaw of the region and retreat of the ice sheet left central Illinois with its present characteristic flat topography.[5]
Because of its central location, Macon County is often referred to as "The Heart of Illinois."[6]
In recent years, average temperatures in the county seat of Decatur have ranged from a low of 17 °F (−8 °C) in January to a high of 88 °F (31 °C) in July, although a record low of −25 °F (−32 °C) was recorded in February 1905 and a record high of 113 °F (45 °C) was recorded in July 1954. Average monthly precipitation ranged from 1.95 inches (50 mm) in February to 4.54 inches (115 mm) in July.[7]
As of the 2010 United States Census, there were 110,768 people, 45,855 households, and 29,326 families residing in the county.[14] The population density was 190.8 inhabitants per square mile (73.7/km2). There were 50,475 housing units at an average density of 86.9 per square mile (33.6/km2).[4] The racial makeup of the county was 79.3% white, 16.3% black or African American, 1.0% Asian, 0.2% American Indian, 0.7% from other races, and 2.5% from two or more races. Those of Hispanic or Latino origin made up 1.9% of the population.[14] In terms of ancestry, 21.7% were German, 17.0% were American, 12.9% were Irish, and 10.8% were English.[15]
Of the 45,855 households, 29.5% had children under the age of 18 living with them, 45.7% were married couples living together, 14.1% had a female householder with no husband present, 36.0% were non-families, and 30.9% of all households were made up of individuals. The average household size was 2.33 and the average family size was 2.89. The median age was 40.3 years.[14]
The median income for a household in the county was $44,337 and the median income for a family was $57,570. Males had a median income of $48,570 versus $31,568 for females. The per capita income for the county was $24,726. About 10.3% of families and 15.7% of the population were below the poverty line, including 26.1% of those under age 18 and 6.5% of those age 65 or over.[16]
In its early years Macon County favored the Democratic Party, voting for it in every election through 1860. Republican Abraham Lincoln won the county in the 1864 election, and from then until the Great Depression Macon County became solidly Republican, only giving a narrow plurality to Woodrow Wilson in 1912 when the GOP was divided by Theodore Roosevelt's splinter–party run.
The FDR-era New Deal saw the county become more amenable to the Democratic Party again due to its strong industrial base. Macon County voted for the winner in every election from 1920 through 1996 save in 1960, 1968, and 1988, in two of which it voted for a losing Democrat over a winning Republican (Humphrey over Nixon in 1968 and Dukakis over George H. W. Bush in 1988). In 2000, Macon voted for a losing Democrat for the third time since the New Deal, as Al Gore narrowly held the county, but since then the county has once again trended Republican, as George W. Bush carried the county over John Kerry in 2004 with the same vote share as Reagan in his 1984 national landslide. Illinois native Barack Obama did carry the county with a plurality in his sweeping 2008 triumph, but was convincingly defeated by Mitt Romney in the county in 2012. In 2016, Hillary Clinton got the lowest vote share of any Democrat since George McGovern; and while Joe Biden improved on her vote share in 2020, he still failed to match McGovern's percentage.
United States presidential election results for Macon County, Illinois[17]
^Stiff, B. J., and A.K. Hansel, 2004, Quaternary glaciations in Illinois. in Ehlers, J., and P.L. Gibbard, eds., pp. 71-82, Quaternary Glaciations: Extent and Chronology 2: Part II North America, Elsevier, Amsterdam. ISBN0-444-51462-7
