|Lee County, Illinois|
Location in the U.S. state of Illinois
Illinois's location in the U.S.
|Founded||27 February 1839|
|Named for||Henry Lee III|
|• Total||729 sq mi (1,888 km2)|
|• Land||725 sq mi (1,878 km2)|
|• Water||4.1 sq mi (11 km2), 0.6%|
|• ( 2010)||36,031|
|• Density||50/sq mi (20/km2)|
|Time zone||Central: UTC−6/ −5|
The Dixon, IL Micropolitan Statistical Area includes all of Lee County.
The area's first non-native settlers were mostly from the six New England states.  The early nineteenth century saw a wave of westward movement from New England, due largely to completion of the Erie Canal and the end of the Black Hawk War.  
The area that included present-day Lee County was delineated as St. Clair County in 1809. In 1823, a large section of northern St. Clair County was partitioned off as Fulton County. In 1825, the northwestern portion of that county was partitioned off as Putnam County. In 1831, the area was further partitioned into Jo Daviess County. A section of that county was partitioned off in 1836 as Ogle County, and in 1839 the bottom half of Ogle County was split off as Lee County. It is largely understood that the county's name honors "Lighthorse Harry" Lee, an officer in the American Revolutionary War.  An alternative theory suggests the name honors Richard Henry Lee, a member of the Continental Congress (the Declaration of Independence was adopted pursuant to the Lee Resolution).
|Climate chart ( explanation)|
In recent years, average temperatures in the county seat of Dixon have ranged from a low of 10 °F (−12 °C) in January to a high of 82 °F (28 °C) in July, although a record low of −27 °F (−33 °C) was recorded in January 1999 and a record high of 110 °F (43 °C) was recorded in July 1936. Average monthly precipitation ranges from 1.43 inches (36 mm) in February to 4.88 inches (124 mm) in June. 
|U.S. Decennial Census
1790-1960  1900-1990 
1990-2000  2010-2013 
As of the 2010 United States Census, there were 36,031 people, 13,758 households, and 9,064 families residing in the county.  The population density was 49.7 inhabitants per square mile (19.2/km2). There were 15,049 housing units at an average density of 20.8 per square mile (8.0/km2).  The racial makeup of the county was 90.9% white, 4.8% black or African American, 0.7% Asian, 0.2% American Indian, 1.9% from other races, and 1.5% from two or more races. Those of Hispanic or Latino origin made up 5.0% of the population.  In terms of ancestry, 38.0% were German, 18.8% were Irish, 8.4% were English, and 8.2% were American. 
Of the 13,758 households, 30.0% had children under the age of 18 living with them, 51.2% were married couples living together, 10.0% had a female householder with no husband present, 34.1% were non-families, and 28.8% of all households were made up of individuals. The average household size was 2.41 and the average family size was 2.94. The median age was 42.0 years. 
The median income for a household in the county was $48,502 and the median income for a family was $60,759. Males had a median income of $42,114 versus $30,920 for females. The per capita income for the county was $24,440. About 7.6% of families and 9.6% of the population were below the poverty line, including 11.8% of those under age 18 and 6.5% of those age 65 or over. 
Lee County is divided into twenty-two townships:
Since the election of 1860 the Republican party candidate for president has won Lee County, Illinois with only one exception, that being in 1912 when Theodore Roosevelt won the county while running as a member of the Progressive Party, unofficially known as the "Bull Moose" party.
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