The city bills itself as "The Crossroads of Opportunity" because of its location at the intersection of two major Interstate highways: I-57 running from Chicago, IL to Miner, MO, and I-70 running from Utah to Maryland. Thus, Effingham has a broad range of restaurants, lodging, and shopping facilities. A 198-foot (60 m) steel cross symbolizes the city as the crossroads of opportunity, and for the city's Christian heritage.
Effingham is also located on U.S. Highway 40, the historic National Road.
As of the census of 2000, there were 12,384 people, 5,330 households, and 3,187 families residing in the city. The population density was 1,428.9 people per square mile (551.5/km²). There were 5,660 housing units at an average density of 653.0/sq mi (252.1/km²). The racial makeup of the city was 97.79% White, 0.36% African American, 0.19% Native American, 0.59% Asian, 0.38% from other races, and 0.69% from two or more races. Hispanic or Latino of any race were 1.04% of the population.
There were 5,330 households out of which 29.9% had children under the age of 18 living with them, 45.0% were married couples living together, 11.4% had a female householder with no husband present, and 40.2% were non-families. 36.1% of all households were made up of individuals and 15.9% had someone living alone who was 65 years of age or older. The average household size was 2.25 and the average family size was 2.96.
In the city the population was spread out with 24.9% under the age of 18, 9.0% from 18 to 24, 27.7% from 25 to 44, 20.2% from 45 to 64, and 18.1% who were 65 years of age or older. The median age was 38 years. For every 100 females there were 89.3 males. For every 100 females age 18 and over, there were 84.2 males.
The median income for a household in the city was $34,761, and the median income for a family was $45,902. Males had a median income of $31,442 versus $21,543 for females. The per capita income for the city was $19,132. About 6.5% of families and 9.6% of the population were below the poverty line, including 12.9% of those under age 18 and 7.9% of those age 65 or over.