According to the U.S. Census Bureau, the county has a total area of, of which is land and is water.
Climate and weather
In recent years, average temperatures in the county seat of Lincoln have ranged from a low of in January to a high of in July, although a record low of was recorded in December 1914 and a record high of was recorded in July 1936. Average monthly precipitation ranged from in February to in May.
According to the 2010 United States Census, there were 30,305 people, 11,070 households, and 7,274 families residing in the county. The population density was. There were 12,107 housing units at an average density of. The racial makeup of the county was 89.1% white, 7.5% black or African American, 0.6% Asian, 0.2% American Indian, 1.2% from other races, and 1.3% from two or more races. Those of Hispanic or Latino origin made up 2.9% of the population. In terms of ancestry, 30.9% were German, 17.4% were American, 13.1% were Irish, and 10.8% were English. Of the 11,070 households, 29.7% had children under the age of 18 living with them, 50.3% were married couples living together, 10.6% had a female householder with no husband present, 34.3% were non-families, and 29.2% of all households were made up of individuals. The average household size was 2.34 and the average family size was 2.85. The median age was 39.4 years. 14.4% of the population were living in group quarters including 11.4% of the population institutionalized. The median income for a household in the county was $48,999 and the median income for a family was $63,245. Males had a median income of $43,940 versus $31,783 for females. The per capita income for the county was $22,063. About 6.8% of families and 9.8% of the population were below the poverty line, including 15.1% of those under age 18 and 5.2% of those age 65 or over.
In the period following the Civil, War Logan was a swing county, following the popular vote winner in every election up to 1936 except those of 1900 and 1916. Since 1940, when its isolationist sentiment drove voters to Wendell Willkie, Logan has become a strongly Republican county. No Democratic Presidential candidate has won Logan County since Lyndon Johnson’s 1964 landslide over Barry Goldwater. In fact, apart from Johnson, Illinoian Barack Obama in 2008 is the solitary Democrat to reach forty percent in the past nineteen elections.
