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Population and Demography of Illinois
Illinois is a state in the Midwestern region of the United States. Its borders are Wisconsin to the north; Lake Michigan to the northeast, Indiana to the east, Kentucky to the southeast, Missouri to the west, and Iowa to the northwest.
Illinois is the sixth most populous state in the United States. The total Land area of Illinois is 55,593 square miles, with a population density of 232 people per square mile. As per the United States Census Bureau, the population of Illinois in 2020 is 12,812,508 (12.8 million)
Estimated Population of Illinois in 2024 – 12,549,689 or 12.5 million
Decadal Growth (2010-2020)
Illinois has a population growth rate of -0.1% during 2010-2020. It has had a population decrease of 18,124 since 2010.
| Illinois | Census 2020 |
| Total Population | 12,812,508 |
| Population Rank | 6th |
| Total Land Area | 55,593 sq mi (143,969 km2) |
| Area Rank | 25 |
| Population Density | 232/sq mi (89.4/km2) |
| Median Age | 37.4 years |
Source: US Census 2020
Illinois Historical Population
In the year 1910 Population of Illinois was 5.6 million and in 2020 it reached 12.8 million, an increase of almost 7.2 million.
Let’s look at the decade population & percentage change from the Year 1910 to 2020.
| Year | Population | Percentage Change |
| 2020 | 12,812,508 | -0.1 |
| 2010 | 12,830,632 | 3.3 |
| 2000 | 12,419,293 | 8.6 |
| 1990 | 11,430,602 | 0.0 |
| 1980 | 11,426,518 | 2.8 |
| 1970 | 11,113,976 | 10.2 |
| 1960 | 10,081,158 | 15.7 |
| 1950 | 8,712,176 | 10.3 |
| 1940 | 7,897,241 | 3.5 |
| 1930 | 7,630,654 | 17.7 |
| 1920 | 6,485,280 | 15.0 |
| 1910 | 5,638,591 | 16.9 |
Source: US Census 2020
Demography of Illinois
Religion and Affilations
Christianity is the majority religion in Illinois followed by 71% of the population. The largest Christian denomination in Illinois is Protestant (43%) followed by Roman Catholics (28%) Next comes the Unaffiliated population, 22% of the population doesn’t follow or adhere to any faith or religion.
Other non-Christian-based religions and faiths followed by 6% of the population include Jews (2%), Hinduism (1%), Buddhism(1%), and other smaller faiths.
For more details read Religion in Illinois
Race and Ethnicity
In 2020, the White alone (non-Hispanic) population was the largest racial or ethnic group in Illinois, comprising 58.32% of the total population. It was followed by the Hispanic or Latino population whose share was 18.24%. Black or African American was the third largest group at 13.86%. Asian population also has a good percentage in Illinois e with a share of 5.83%. Two or more races are at 3.24%.
For more Details read Race and Ethnicity in Illinois
Ancestry in Illinois
As per Census Studies & estimate German, Irish, Polish, Italian, and English have made the five largest ancestry groups in Illinois. Illinois has the 14th-highest percentage of African Americans and the 5th-highest Hispanic population in the country with over 2 million Hispanic residents.
For more Details read Race and Ethnicity in Illinois
Cities and Counties in Illinois
Chicago is the largest and most populated city in Illinois. The next largest is Aurora followed by Naperville, Joilet, and Rockford. As of 2022, Illinois is divided into 102 counties. Cook County is the largest county in Illinois, housing 5,238,216 people. The next largest county is neighboring Dupage, with 933,736 people. As of 2022, Illinois is divided into 102 counties.
read more about Cities and Counties in Illinois
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