Lee County is a county located in the U.S. state of Illinois. According to the 2020 census, it has a population of 34,145. Its county seat is Dixon. 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).
President Ronald Reagan lived in Dixon as a boy and attended Dixon High School.
According to the US Census Bureau, the county has a total area of , of which is land and (0.6%) is water.
In recent years, average temperatures in the county seat of Dixon have ranged from a low of in January to a high of in July, although a record low of was recorded in January 1999 and a record high of was recorded in July 1936. Average monthly precipitation ranges from in February to in June.
As of the 2020 census, the county had a population of 34,145. The median age was 43.7 years. 19.7% of residents were under the age of 18 and 20.0% of residents were 65 years of age or older. For every 100 females there were 112.0 males, and for every 100 females age 18 and over there were 114.1 males age 18 and over.
The racial makeup of the county was 85.3% White, 5.5% Black or African American, 0.3% American Indian and Alaska Native, 0.7% Asian, <0.1% Native Hawaiian and Pacific Islander, 2.7% from some other race, and 5.5% from two or more races. Hispanic or Latino residents of any race comprised 6.8% of the population.
46.8% of residents lived in urban areas, while 53.2% lived in rural areas.
There were 13,589 households in the county, of which 26.9% had children under the age of 18 living in them. Of all households, 47.2% were married-couple households, 19.5% were households with a male householder and no spouse or partner present, and 25.1% were households with a female householder and no spouse or partner present. About 30.9% of all households were made up of individuals and 14.1% had someone living alone who was 65 years of age or older.
There were 14,985 housing units, of which 9.3% were vacant. Among occupied housing units, 72.9% were owner-occupied and 27.1% were renter-occupied. The homeowner vacancy rate was 2.2% and the rental vacancy rate was 9.6%.
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 . There were 15,049 housing units at an average density of . 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, together with neighboring Ogle County, the most consistently Republican county in Illinois. It is one of very few counties in the United States to have never supported a Democrat for President since the Civil War. The only occasion when the Republican candidate did not win the county in this time was in 1912, when Theodore Roosevelt carried it while running as a member of the Progressive Party, unofficially known as the "Bull Moose" party.
As of 2018, Lee County is in the 16th congressional district, the 45th legislative district, and the 74th and 90th representative districts.
K-12 school districts include:
Secondary school districts include:
Elementary school districts include: