phone number: fax number: emergency response program: 928-428-0110: 928-428-8074: public health: 928-428-0110: 928-428-8074
Springfield, Illinois. Springfield is the capital of the U.S. state of Illinois and the county seat of Sangamon County. The city's population of 116,250 as of the 2010 U.S. Census makes it the state's sixth most populous city. It is the largest city in central Illinois.
The 2016 Springfield, Illinois, population is 116,565. There are 1,955 people per square mile (population density). The median age is 38.7. The US median is 37.4. 44.11% of people in Springfield, Illinois, are married. 14.83% are divorced.