|Area||0.3 sq mi (1 km2)|
|- land||0.3 sq mi (1 km2)|
|Density||1,411.6 /sq mi (545 /km2)|
|- summer (DST)||CDT (UTC-5)|
Location of Sigel within Illinois
|Wikimedia Commons: Sigel, Illinois|
Sigel is located at (39.226214, -88.495161).
According to the United States Census Bureau, the town has a total area of 0.3 square miles (0.7 km²), of which, 0.3 square miles (0.7 km²) of it is land and 3.57% is water.
As of the census of 2000, there were 386 people, 141 households, and 97 families residing in the town. The population density was 1,411.6 people per square mile (552.0/km²). There were 154 housing units at an average density of 563.2/sq mi (220.2/km²). The racial makeup of the town was 99.22% White, 0.52% from other races, and 0.26% from two or more races. Hispanic or Latino of any race were 1.81% of the population.
There were 141 households out of which 35.5% had children under the age of 18 living with them, 51.8% were married couples living together, 12.1% had a female householder with no husband present, and 30.5% were non-families. 29.8% of all households were made up of individuals and 14.2% had someone living alone who was 65 years of age or older. The average household size was 2.72 and the average family size was 3.38.
In the town the population was spread out with 31.3% under the age of 18, 10.4% from 18 to 24, 27.2% from 25 to 44, 16.3% from 45 to 64, and 14.8% who were 65 years of age or older. The median age was 33 years. For every 100 females there were 103.2 males. For every 100 females age 18 and over, there were 89.3 males.
The median income for a household in the town was $36,607, and the median income for a family was $51,500. Males had a median income of $34,375 versus $22,656 for females. The per capita income for the town was $15,933. About 2.4% of families and 3.9% of the population were below the poverty line, including 1.7% of those under age 18 and 9.8% of those age 65 or over.