Berlin is a village in Sangamon County, Illinois, United States. The population was 140 at the 2000 census. It is part of the Springfield, Illinois Metropolitan Statistical Area. It is also colloquially called "Old Berlin", due to the larger village of New Berlin 1.4 miles south.

Berlin is located at 39°45′25″N 89°54′12″W / 39.75694°N 89.90333°W / 39.75694; -89.90333 (39.756808, -89.903407).

According to the 2010 census, Berlin has a total area of 1 square mile (2.59 km), all land.

Historical population

Census	Pop.	Note	%±
1880	287		—
1890	260		−9.4%
1900	256		−1.5%
1910	251		−2.0%
1920	241		−4.0%
1930	222		−7.9%
1940	215		−3.2%
1950	218		1.4%
1960	197		−9.6%
1970	175		−11.2%
1980	210		20.0%
1990	180		−14.3%
2000	140		−22.2%
2010	180		28.6%
2020	141		−21.7%
U.S. Decennial Census

As of the census of 2000, there were 140 people, 62 households, and 46 families residing in the village. The population density was 140.6 inhabitants per square mile (54.3/km). There were 69 housing units at an average density of 69.3 per square mile (26.8/km). The racial makeup of the village was 99.29% White and 0.71% African American.

There were 62 households, out of which 21.0% had children under the age of 18 living with them, 62.9% were married couples living together, 8.1% had a female householder with no husband present, and 24.2% were non-families. 19.4% of all households were made up of individuals, and 11.3% had someone living alone who was 65 years of age or older. The average household size was 2.26 and the average family size was 2.51.

In the village, the population was spread out, with 16.4% under the age of 18, 5.0% from 18 to 24, 29.3% from 25 to 44, 27.9% from 45 to 64, and 21.4% who were 65 years of age or older. The median age was 44 years. For every 100 females, there were 100.0 males. For every 100 females age 18 and over, there were 98.3 males.

The median income for a household in the village was $38,125, and the median income for a family was $41,042. Males had a median income of $29,375 versus $28,750 for females. The per capita income for the village was $15,079. There were 23.1% of families and 21.1% of the population living below the poverty line, including 24.1% of under eighteens and 30.8% of those over 64.