The level of street-network sprawl in new development in Illinois peaked in 1991-2005. To get a sense of how street development has changed in Illinois, we can consider three of its most populous cities: Chicago, Aurora and Bolingbrook. Out of the three cities, Chicago and Aurora do not follow the same trend as the region. The level of street-network sprawl in new development in Chicago rose steadily. The level of street-network sprawl in new development in Aurora peaked in 1976-1990.

How do development practices in Illinois fare in comparison to others in United States? Most recently in 2006-2020, street construction in Illinois was the 15th-most disconnected out of the 44 regions in United States. Its position in the ranks since 1975 has fallen; relative to other regions in United States, street construction in Illinois has become more connected. Illinois ranked 8th in 1975, 18th in 1976-1990, 18th in 1991-2005 and 15th in 2006-2020.

As of 2020, the city with the most disconnected street network in Illinois is Bolingbrook with an SNDi of 3.73, which is relatively sprawly. Conversely, the most connected city is Champaign with an SNDi of 1.86, which is very well-connected. See trends for these cities: Champaign, Bolingbrook

The level of street-network sprawl in the aggregate network in Illinois rose steadily. To get a sense of how the aggregate street network has changed in Illinois, we can consider three of its most populous cities: Chicago, Aurora and Bolingbrook. Out of the three cities, Bolingbrook does not follow the same trend as the region. The level of street-network sprawl in the aggregate network in Bolingbrook peaked in 1991-2005.

To date, Illinois is the 8th-most disconnected out of the 44 regions in United States. Its position in the ranks since 1975 has not changed. Illinois ranked 8th in 1975, 9th in 1976-1990, 9th in 1991-2005 and 8th in 2006-2020.