Unites States >> States >> Illinois
Illinois Population Overview (2026 Projection)
llinois is a Midwestern state in the United States, bordered by Wisconsin to the north, Lake Michigan to the northeast, Indiana to the east, Kentucky to the southeast, Missouri to the southwest, and Iowa to the northwest. It is the sixth-most populous state in the U.S. and covers a total land area of 55,593 square miles.
According to the U.S. Census Bureau, Illinois recorded a population of 12,812,508 in the 2020 Census. The latest population estimate (July 1, 2024) places Illinois’s population at 12,710,158 (12.7 million), showing a slight decline since 2020.
Recent Census trends indicate that net domestic out-migration, partially offset by international migration and natural population change, has resulted in relatively stable population levels. Illinois’s population is expected to remain steady with minor year-to-year variation in the near term.
Projected Population of Illinois (2026): ~ 12.7 million
Illinois Population Growth (2010–2020)
Illinois recorded a population growth rate of -0.1% between 2010 and 2020, resulting in a slight population decline of approximately 18,124 residents over the decade.
Illinois Census Snapshot (2020)
| 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
Illinois’s population has more than doubled over the past century, rising from about 5.6 million in 1910 to 12.8 million in 2020, an increase of nearly 7.2 million residents. The state experienced rapid growth in the early 20th century, particularly between 1910 and 1960, while growth slowed in the later decades. Between 2010 and 2020, Illinois recorded a slight population decline of 0.1%, reflecting stable but modest demographic changes.
Decadal Population Change (1910–2020)
| 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
Illinois Demographics (Summary)
Religion in Illinois (Overview)
Christianity is the largest religion in Illinois, followed by approximately 71% of the population. The major Christian denominations are Protestant (43%) and Roman Catholic (28%). The unaffiliated population accounts for about 22%, representing residents who do not follow any religion.
Other non-Christian religions are followed by roughly 6% of the population, including Judaism (2%), Hinduism (1%), Buddhism (1%), and other smaller faiths.
🔗 Read more: Religion in Illinois
Race and Ethnicity in Illinois (Overview)
In 2020, the White alone (non-Hispanic) population was the largest racial or ethnic group in Illinois, comprising 58.3% of the total population. It was followed by Hispanic or Latino (18.2%), Black or African American (13.9%), and Asian (5.8%) populations. Residents identifying with two or more races accounted for 3.2% of the population.
Ancestry in Illinois (Overview)
The most common ancestry groups in Illinois are German, Irish, Polish, Italian, and English. The state also ranks 14th in the U.S. for African American population and 5th for Hispanic population, with over 2 million Hispanic residents.
🔗 Read more: Race and Ethnicity in Illinois
Cities and Counties in Illinois
Chicago is the largest and most populous city in Illinois. Other major cities include Aurora, Naperville, Joliet, and Rockford.
Illinois is divided into 102 counties. Cook County is the most populous, with approximately 5.24 million residents, followed by DuPage County with around 933,700 residents.
🔗 Read more: Cities and Counties in Illinois
English
Español
Português
Deutsch