You can tell a lot about an area by the state of its housing — how big, how old, how many multi-unit buildings and how many single units.

Information from the United States Census Bureau, compiled by homefacts.com, shows what kinds, ages and sizes of homes are most prevalent in the 10 most populous counties in the state. The numbers reflect the lifestyles of the counties’ residents.

Cook County, the state’s largest and most heavily urban county, has more homes in multi-unit buildings than single-units. It’s the only county with that distinction. It also had the oldest collection of homes, with most construction happening before 1970, showing that the area has been highly populous for longer than other counties.

The collar counties that border Cook —  DuPage, Kane, Lake, McHenry and Will — have the biggest and newest homes.

Here’s what homefacts.com found about housing in the 10 most populous counties in Illinois:

Cook County

Type of building: 45.2 percent are single-unit buildings, 54.1 percent are multi-unit buildings

Number of rooms: 57.8 percent have five or fewer rooms, 42.1 percent have more than five rooms

Year built: 54 percent were built before 1970, 45.8 percent were built in 1970 or later

DuPage County

Type of building: 72.1 percent are single-unit buildings, 27.7 percent are multi-unit buildings

Number of rooms: 40.4 have five or fewer rooms, 59.4 percent have more than five rooms

Year built: 33 percent were built before 1970, 66.7 percent were built in 1970 or later

Lake County

Type of building: 78.9 percent are single-unit buildings, 19.2 percent are multi-unit buildings

Number of rooms: 38 percent have five or fewer rooms, 62.1 percent have more than five rooms

Year built: 33.8 percent were built before 1970, 66.3 percent were built in 1970 or later

Will County

Type of building: 86.1 percent are single-unit buildings, 12.5 percent are multi-unit buildings

Number of rooms: 32.6 percent have five or fewer rooms, 67.4 percent have more than five rooms

Year built: 25.5 percent were built before 1970, 74.6 percent were built in 1970 or later

Kane County

Type of building: 79.9 percent are single-unit buildings, 19.1 percent are multi-unit buildings

Number of rooms: 39.4 percent have five or fewer rooms, 60.6 percent have more than five rooms

Year built: 37.5 percent were built before 1970, 62.5 percent were built after 1970

McHenry County

Type of building: 87.8 percent are single-unit buildings, 11.8 percent are multi-unit buildings

Number of rooms: 31.4 have five or fewer rooms, 68.6 percent have more than five rooms

Year built: 28.2 percent were built before 1970, 71.7 percent were built in 1970 or later

Winnebago County

Type of building: 73.5 percent are single-unit buildings, 24.9 percent are multi-unit buildings

Number of rooms: 47 percent have five or fewer rooms, 53.1 percent have more than five rooms

Year built: 52 were built before 1970, 47.8 percent were in 1970 or later

St. Clair County

Type of building: 73 percent are single-unit buildings, 21.2 percent are multi-unit buildings

Number of rooms: 51.4 percent have five or fewer rooms, 48.7 percent have more than five rooms

Year built: 51.3 percent were built before 1970, 48.7 percent were built in 1970 or later

Madison County

Type of building: 80.6 are single-unit buildings, 15.8 percent are multi-unit buildings

Number of rooms: 47.6 percent have five or fewer rooms, 52.3 percent have more than five rooms

Year built: 57 percent were built before 1970, 43.1 percent were built in 1970 or later

Champaign County

Type of building: 62.2 percent are single-unit buildings, 34.7 percent are multi-unit buildings

Number of rooms: 51.4 percent have five or fewer rooms, 48.5 percent have more than five rooms

Year built: 43 percent were built before 1970, 57 percent were built in 1970 or later

Sangamon County

Type of building: 76 percent are single-unit buildings, 17.9 percent are multi-unit buildings

Number of rooms: 47.5 have five or fewer rooms, 52.6 percent have more than five rooms

Year built: 48 percent were built before 1970, 51.9 percent were built in 1970 or later

Peoria County

Type of building: 76 percent are single-unit buildings, 22 percent are multi-unit buildings

Number of rooms: 51.4 percent have five or fewer rooms, 48.4 percent have more than five rooms

Year built: 58.6 percent were built before 1970, 41.4 percent were built in 1970 or later

McLean County

Type of building: 66.7 percent are single-unit buildings, 28.7 percent are multi-unit buildings

Number of rooms: 43.9 percent have five or fewer rooms, 56.2 have more than five rooms

Year built: 37.9 percent were built before 1970, 62.3 were built in 1970 or later

Rock Island County

Type of building: 74.9 percent are single-unit buildings, 21.9 percent are multi-unit buildings

Number of rooms: 47.3 percent have five or fewer rooms, 51.8 percent have more than five rooms

Year built: 68.9 percent were built before 1970, 31.2 percent were built in 1970 or later

Tazewell County

Type of building: 83.3 percent are single-unit buildings, 14.4 percent are multi-unit buildings

Number of rooms: 44.5 percent have five or fewer rooms, 55.6 have more than five rooms

Year built: 56.3 percent were built before 1970, 43.7 percent were built after 1970

Kendall County

Type of building: 90.8 percent are single-unit buildings, 8.9 percent are multi-unit buildings

Number of rooms: 31.9 percent have five or fewer rooms, 68.1 percent have more than five rooms

Year built: 14.4 percent were built before 1970, 85.5 percent were built in 1970 or later

LaSalle County

Type of building: 81.8 percent are single-unit buildings, 13.1 percent are multi-unit buildings

Number of rooms: 48.2 percent have five or fewer rooms, 51.8 percent have more than five rooms

Year built: 63.4 percent were built before 1970, 36.6 percent were built in 1970 or later

Kankakee County

Type of building: 76.3 percent are single-unit buildings, 17.5 percent are multi-unit buildings

Number of rooms: 46 percent have five or fewer rooms, 54 percent have more than five rooms

Year built: 47 percent were built before 1970, 52.9 percent were built in 1970 or later

Macon County

Type of building: 78.2 percent are single-unit buildings, 18.5 percent are multi-unit buildings

Number of rooms: 49.8 percent have five or fewer rooms, 50.2 percent have more than five rooms

Year built: 69.7 percent were built before 1970, 39.4 percent were built in 1970 or later

DeKalb County

Type of building: 67.1 percent are single-unit buildings, 30.1 are multi-family units

Number of rooms: 52.3 percent have five or fewer rooms, 47.7 percent have more than five rooms

Year built: 41.9 percent were built before 1970, 58.1 percent were built in 1970 or later

Vermillion County

Type of building: 78.7 percent are single-unit buildings, 16.5 percent are multi-unit buildings

Number of rooms: 51.3 percent have five or fewer rooms, 48.6 percent have more than five rooms

Year built: 64.6 percent were built before 1970, 35.4 percent were built in 1970 or later

Adams County

Type of building: 81.6 percent are single-unit buildings, 15.2 percent are multi-unit buildings

Number of rooms: 43.6 percent have five or fewer rooms, 56 percent have more than five rooms

Year built: 56.1 percent were built before 1970, 43.9 percent were built in 1970 or later

Williamson County

Type of building: 75.3 percent are single-unit buildings, 12.7 percent are multi-unit buildings

Number of rooms: 53.4 percent have five or fewer rooms, 46.7 percent have more than five rooms

Year built: 44.9 percent were built before 1970, 55.1 percent were built in 1970 or later

Jackson County

Type of building: 52.2 percent are single-unit buildings, 33.1 are multi-unit buildings

Number of rooms: 63.5 percent have five or fewer rooms, 36.6 percent have more than five rooms

Year built: 38.4 percent were built before 1970, 61.6 percent were built after in 1970 or later

Whiteside County

Type of building: 82.1 percent are single-unit buildings, 15 percent are multi-unit buildings

Number of r0oms: 41.7 percent have five or fewer rooms, 58.4 percent have more than five rooms

Year built: 64.8 percent were built before 1970, 35.2 percent were built in 1970 or later

In comparison, the national averages for these indicators are as follows:

Type of building: 67.4 percent are single-unit buildings, 32.6 percent are multi-unit buildings

Number of rooms: 50.8 have five or fewer rooms, 49.1 percent have more than five rooms

Year built: 40.6 percent were built before 1970, 57 percent were built in 1970 or later

Broken down more specifically, the percentage of homes built in an area broken down by decade of construction also shows when building was slow (relatively fewer homes in every county were built in the 1940s, when World War II presumably took up most construction energy, and very few homes in each county have been built since 2005, during the housing market crisis and Great Recession). Most counties showed periods of high construction in the 1950s, 1970s and from 2000 to 2004.

NEXT ARTICLE: What’s the housing inventory in your county?

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