DuPage County ( ) is located in the U.S. state of Illinois, and is one of the collar counties of the Chicago metropolitan area. As of the 2020 census, the population was 932,877, making it Illinois' second-most populous county. Its county seat is Wheaton.

Known for its vast tallgrass prairies, DuPage County has become mostly developed and suburbanized, although some pockets of farmland remain in the county's western and northern parts. Located in the Rust Belt, the area is one of few in the region whose economy quickly became dependent on the headquarters of several large corporations due to its close proximity to Chicago. As quarries closed in the 1990s, land that was formerly used for mining and plants was converted into mixed-use, master-planned developments to meet the growing tax base. The county has a mixed socioeconomic profile and residents of Hinsdale include some of the wealthiest people in the Midwest. On the whole, the county enjoys above average median household income levels and low overall poverty levels when compared to the national average.

History Prior to European-American settlement, the area that is now DuPage County was inhabited by the Potawatomi people. By 1800, the Potawatomi had established 4 major villages along local rivers within the county, and had a network of trails crisscrossing the area. The first European-American settlers arrived in what is now DuPage County in 1832, and the Potawatomi population was forced out of the region only one year later after ceding their land in the Treaty of Chicago. DuPage County was officially formed on February 9, 1839, out of Cook County. The county took its name from the DuPage River, which was, in turn, named after a French fur trapper, DuPage. The first written history to address the name, the 1882 History of DuPage County, Illinois, by Rufus Blanchard, relates:

The DuPage River had, from time immemorial, been a stream well known. It took its name from a French trader who settled on this stream below the fork previous to 1800. Hon. H. W. Blodgett, of Waukegan, informs the writer that J. B. Beaubien had often spoken to him of the old Frenchman, Du Page, whose station was on the bank of the river, down toward its mouth, and stated that the river took its name from him. The county name must have the same origin. Col Gurden S. Hubbard, who came into the country in 1818, informs the writer that the name DuPage, as applied to the river then, was universally known, but the trader for whom it was named lived there before his time. Mr. Beaubien says it is pronounced Du Pazhe (having the sound of ah, and that the P should be capitalized). This was in reply to Mr. Blodgett's inquiry of him concerning the matter.

The first white settler in DuPage County was Bailey Hobson who, with Lewis Stewart, built a house in 1831 for the Hobson family at a site about south of present-day downtown Naperville. Hobson later built a mill to serve surrounding farmers. Today, the Hobson house still stands on Hobson Road in Naperville, and the location of the mill is commemorated with a millstone and monument in today's Pioneer Park.

Geography According to the U.S. Census Bureau, the county has a total area of , of which is land and (2.6%) is water. The DuPage River and the Salt Creek flow through DuPage County. According to the Forest Preserve District of DuPage County, the highest point in the county is located at the Mallard Lake Landfill, which at its highest point is above mean sea level.

Up to 60% of the county’s water was supplied by shallow dolomite wells until more communities began receiving water from Lake Michigan via City of Chicago in the 1990s.

Climate

In recent years, average temperatures in the county seat of Wheaton have ranged from a low of in January to a high of in July, although a record low of was recorded in January 1985 and a record high of was recorded in July 1995. Average monthly precipitation ranged from in February to in August.

Adjacent counties Counties that are adjacent to DuPage include: Cook County (east and north) Will County (south) Kendall County (southwest; counties meet at a corner) Kane County (west)

Demographics

2020 Census As of the 2020 census, the county had a population of 932,877, and the median age was 40.1 years. 22.4% of residents were under the age of 18 and 16.5% were 65 years of age or older, and for every 100 females there were 95.9 males (93.4 males for every 100 females age 18 and over).

The racial makeup of the county was 66.1% White, 4.9% Black or African American, 0.6% American Indian and Alaska Native, 12.8% Asian, fewer than 0.1% Native Hawaiian and Pacific Islander, 6.7% from some other race, and 8.9% from two or more races, while Hispanic or Latino residents of any race comprised 15.5% of the population.

99.8% of residents lived in urban areas, while 0.2% lived in rural areas.

There were 348,216 households in the county, of which 32.4% had children under the age of 18 living in them, 55.9% were married-couple households, 15.3% were households with a male householder and no spouse or partner present, and 23.7% were households with a female householder and no spouse or partner present.

There were 364,970 housing units, of which 4.6% were vacant. Among occupied housing units, 72.3% were owner-occupied and 27.7% were renter-occupied, with a homeowner vacancy rate of 1.2% and a rental vacancy rate of 7.1%.

Racial and ethnic composition +DuPage County, Illinois – Racial and ethnic compositionRace / Ethnicity (NH = Non-Hispanic)Pop 1980Pop 1990Pop 2000Pop 2010 Pop 2020% 1980% 1990% 2000% 2010% 2020White alone (NH)612,606691,833711,966646,130591,44192.98%88.51%78.74%70.47%63.40%Black or African American alone (NH)7,74215,11926,97741,02444,2011.18%1.93%2.98%4.47%4.74%Native American or Alaska Native alone (NH)5458449129928730.08%0.11%0.10%0.11%0.09%Asian alone (NH)18,66638,93170,90891,793118,9822.83%4.98%7.84%10.01%12.75%Native Hawaiian or Pacific Islander alone (NH)x included in the Asian category in the 1980 Censusx included in the Asian category in the 1990 Census180171219xx0.02%0.02%0.02%Other race alone (NH)1,9743728701,1813,2990.30%0.05%0.10%0.13%0.35%Mixed race or Multiracial (NH)x not an option in the 1980 Censusx not an option in the 1990 Census10,98214,12729,571xx1.21%1.54%3.17%Hispanic or Latino (any race)17,30234,56781,366121,506144,2912.63%4.42%9.00%13.25%15.47%Total658,835781,666904,161916,924932,877 100.00%100.00%100.00%100.00%100.00%

Racial / Ethnic Profile of places in DuPage County, Illinois (2020 census) Racial / Ethnic Profile of places in DuPage County, Illinois (2020 Census)Following is a table of towns and census designated places in DuPage County, Illinois. Data for the United States (with and without Puerto Rico), the state of Illinois, and DuPage County itself have been included for comparison purposes. The majority racial/ethnic group is coded per the key below. Communities that extend into and adjacent county or counties are delineated with a followed by an accompanying explanatory note. The full population of each community has been tabulated including the population in adjacent counties. Majority minority with no dominant groupMajority WhiteMajority BlackMajority HispanicMajority Asian