In Illinois, the child labor laws are significantly less than most other states.
On very rare occasions in other states in the Union, children below 16 can work (if they are working for someone who is not their parents). In Illinois, children as young as 14 year old can be working as casiers, or other non-labor-intensive jobs. This does however, follow federal regulations which every other state has to follow.
No state can allow employed children under the age of 18 to operate heavy machinery at their job unless they do work for their parents, then the line between legal employment and illegal job requirements becomes skewed. Illinois' child labor law is more strict than California's labor laws however.
In California, a child as young as 10 can work in agriculture, whereas in Illinois the same child must be at least 12 years of age. Even the standard working age is different. Illinois however is a lot more like the rest of the Union and their child labor laws in the sense that the standard working age (the age that one's age does not determine if one can work a job, excluding public office) is 18, where California has their standard working age at 21.
There is a small loophole however, for children in Illinois under the age of 16, and working regular jobs. If a child wants to work at age 14, they can so long as they do not work during school hours, and they work at a State sponsored job. The definition of state sponsored in this case is that the state deemed a specific job type safe enough for a child under the age of 18, but older than 14 to work at. The state of Illinois however is allowing children to work at coal mines, lumber and brick yards, and manufacturing establishments.
For more information there are a number of resources that are available for you to find out about what working laws affect you as well as what kind of work is available for young adults like you to perform at your age. Please check out the resources available from the United States Department of Labor and the Illinois Department of Labor to find out more. Both departments have online websites that are reliably navigable and should provide you with the information you need to get started with your work!
Happy hunting and best of luck in your job search.