Marshall County in 1843, when its eastern border was extended to bring it to its current size
Geography
According to the U.S. Census Bureau, the county has a total area of 399 square miles (1,030 km2), of which 387 square miles (1,000 km2) is land and 12 square miles (31 km2) (2.9%) is water.[4] The county is distinctly bisected by the Illinois River, splitting the county into two uneven sections.[citation needed]
In recent years, average temperatures in the county seat of Lacon have ranged from a low of 15 °F (−9 °C) in January to a high of 87 °F (31 °C) in July, although a record low of −27 °F (−33 °C) was recorded in January 1999 and a record high of 103 °F (39 °C) was recorded in July 2005. Average monthly precipitation ranged from 1.55 inches (39 mm) in January to 4.20 inches (107 mm) in May.[5]
U.S. Decennial Census[7] 1790-1960[8] 1900-1990[9] 1990-2000[10] 2010[11]
As of the 2010 United States census, there were 12,640 people, 5,161 households, and 3,549 families living in the county.[12] The population density was 32.7 inhabitants per square mile (12.6/km2). There were 5,914 housing units at an average density of 15.3 per square mile (5.9/km2).[4] The racial makeup of the county was 97.1% white, 0.4% Asian, 0.3% black or African American, 0.2% American Indian, 1.1% from other races, and 0.9% from two or more races. Those of Hispanic or Latino origin made up 2.5% of the population.[12] In terms of ancestry, 43.0% were German, 16.7% were Irish, 14.4% were English, 7.2% were Italian, 6.2% were American, and 6.1% were Polish.[13]
Of the 5,161 households, 27.4% had children under the age of 18 living with them, 56.7% were married couples living together, 7.7% had a female householder with no husband present, 31.2% were non-families, and 26.8% of all households were made up of individuals. The average household size was 2.40 and the average family size was 2.88. The median age was 44.8 years.[12]
The median income for a household in the county was $49,116 and the median income for a family was $64,781. Males had a median income of $46,793 versus $28,549 for females. The per capita income for the county was $24,991. About 6.8% of families and 9.5% of the population were below the poverty line, including 11.4% of those under age 18 and 7.0% of those age 65 or over.[14]
In its early days Marshall County was a swing county, voting for winning Whig candidate William Henry Harrison in 1840 but otherwise supporting the Democratic Party until 1852. Its reputation as a swing county was to be sustained with the growth of the Republican Party: it voted for the winning candidate in every election from 1852 to 1912 except 1884 and 1888.[citation needed]
Since World War I, Marshall has generally been a strongly Republican county. Only two Democrats – Franklin D. Roosevelt in 1932 and 1936 plus Lyndon Johnson in 1964 – have gained an absolute majority in Marshall County over the past twenty-six elections, although Bill Clinton won pluralities in both his elections.[citation needed]
United States presidential election results for Marshall County, Illinois[15]
