Illinois Population 2023

The 2015 Census estimates put the population at 12,859,995, which was a decrease from the 2014 numbers. Illinois is one of only 7 states that has a negative growth rate in 2016. At -0.17% per year, it is ahead of only West Virginia. Between 2000 and 2010, the population of Illinois grew by a mere 3.3%, compared to the national average US population growth of 9.7%.

The 2018 population estimates Illinois is the sixth largest state in the USA based on population.

Illinois Surface Area and Population Density

The total area of Illinois is 57,914 square miles, with a population density of 230 people per square mile.

Most of the Illinois population is heavily concentrated in the North East of the state in the metropolitan area of Chicago. Chicago, which is home to 2,720,546 people, remains the largest city in Illinois. This city dwarfs the state's other cities, including the capital of the state. The next largest is Aurora, with 200,661 people.

This marks one of Illinois' defining features -- although it has a large urban population, it is spread through a number of smaller cities. Including Chicago, there are twelve cities (including the city of Springfield, the state's capital) with more than 75,000 people.

Many of these smaller cities make up a part of the Chicago Metropolitan Area (prosaically also known as Chicagoland), which holds between 8.3 and 9.8 million people, depending on how you classify its boundaries.

Cook County is the largest county in Illinois, housing 5,238,216 people. The next largest county is neighboring Dupage, with 933,736 people. Almost half of the Illinois population can be found in just those two counties.

Illinois Gender and Religion Statistics

The median age in Illinois is 37.4 years of age, with a slight gender difference over the state- 50.9% female and 49.1% male.

In religious terms, Illinois shows its preferences with a 71% preference for Christian based faiths, a 6% affiliation with non-Christian based faiths, and 22% of the population being unaffiliated with any particular religion.

Illinois Boundary, Census, and Statehood History

Illinois was included in the Northwest Territory established in 1787 and then in Indiana Territory (1800). Illinois Territory was established in 1809, and included virtually all of present-day Wisconsin and portions of Minnesota and the Upper Peninsula of Michigan. Illinois was admitted as a State on December 3, 1818 with essentially its present boundaries.

In 1790 the Northwest Territory had no census coverage. The population shown for 1800 is the total of two counties and one community in present-day Illinois, at that time part of Indiana Territory. Knox County, Indiana Territory, also included some population in what is now Illinois. In 1810, the returns for the two counties of Illinois Territory included some settlements in present-day Wisconsin. The northern part of the State was not fully covered by the census until 1830.

Illinois Population History

Illinois saw massive growth throughout the 19th century, from a measly 2,458 people in 1800 to nearly 5 million in 1900. This rise made Illinois the 3rd largest state by the turn of the century. Growth continued into the 20th century, albeit at a slower pace.

Illinois Population Growth

In Illinois' cities, population growth has stalled. Chicago was, for much of its early history, one of America's fastest growing cities. Between 1850 and 1930, the city grew by at least 25% each decade, and in some decades it doubled or even tripled in size. However, from the 1960s onwards, Chicago has been steadily shrinking and a city which was home to 3.5 million people in 1960 is home to just 2.7 million today.

Illinois Population Projections

If the current decline continues, Illinois will fall back to the 6th spot in state rankings at the 2020 Census, behind Pennsylvania.

Some estimates expect Illinois to see growth again by 2020, and possibly reach 13.1 million in 2020.

Based on data from the 2010 Census, Illinois has the 14th highest percentage of African Americans across all states. Based on 2011 data, the state also has the 5th highest Hispanic population in the country with over 2 million Hispanic residents, and the 10th highest percentage of Hispanics that account for its diverse total population.

In recent years, Illinois has seen significant declines in its white population, with numbers dropping from 83.5% of the total population in 1970 to 63.3% just 40 years later. According to 2011 data, almost 50% of the population under the age of 1 were minorities.

According to data from 2007, over 1.7 million people in Illinois were foreign-born. This represented, at the time, almost 14% of the population. Over 48% of Illinois' foreign-born inhabitants came from Latin America, while almost one-quarter of the total number came from Asia. It is estimated that over 58% of the total 1.7 million foreign-born inhabitants recorded were not US citizens.

• Illinois has the world's only river that flows backwards.
• Chicago's Lincoln Park Zoo is the country's fourth oldest public zoo.
• Almost 80% of the land in Illinois is farmland.
• The Sears Tower (aka Willis Tower), located in Chicago, is the tallest building in North America.
• In 1865, Illinois ratified the 13th Amendment to abolish slavery. It was the first state to do so.
• There are 102 counties in the state of Illinois.
• The country's 9th largest public library is the Chicago Public Library, which houses over 5 million books.
• Illinois has more units of government than any other state.
• The oldest community in Illinois is Peoria.