Direct from the Illinois DNR Website:
"On October 2, 1975, a State law was passed that requires persons at least twelve years of age and less than sixteen years of age may operate a snowmobile only if:
*they have in possession a valid Snowmobile Safety Education Certificate of Competency issued by the Illinois Department of Natural Resources, Division of Education.
*or they are accompanied on the snowmobile by a parent or guardian or person at least sixteen years of age designated by a parent or guardian."
From the Wisconsin DNR website:
"Snowmobile Age Requirements
Who may operate a snowmobile? -- Any person who is born on or after January 1, 1985 and who has reached the age of 12, must have completed and received a snowmobile safety certificate in order to operate a snowmobile in Wisconsin. The certificate must be carried while operating the snowmobile, and displayed to a law enforcement officer upon demand.
Check class availablility: Upcoming Courses
This does not apply to the operation of snowmobiles upon lands owned or leased by the operator's parent or guardian. As used in this section, "leased lands" does not include lands leased by an organization of which said operator or the operator's parent or guardian is a member.
No person under the age of 12 years may operate a snowmobile unless the person is accompanied either by a parent or guardian or by a person over 18 years of age. Accompanied means to be on the same snowmobile as the operator.
Other states and Provinces that issue a snowmobile safety certificate to snowmobilers will be honored in Wisconsin."
From the Michigan DNR website:
"Required Snowmobile Safety Course
You must successfully complete a snowmobile safety course if you are:
A person who is at least 12 but less than 17 years of age operating a snowmobile without direct supervision of a person 21 years of age or older must have in their immediate possession a valid snowmobile safety certificate.
A person who is at least 12 but less than 17 years of age may not cross a highway or street without having a valid snowmobile safety certificate in their immediate possession.
Snowmobile safety training is recommended for all snowmobile operators. Modern snowmobiles are capable of high rates of speeds over snow and ice. With the countless hazards associated with operating a snowmobile, training is a crucial factor in safe and responsible snowmobile operation.
Michigan Conservation Officers, in cooperation with schools, organizations and associations, take an active role in assuring that all of Michigan's citizens are given the opportunity to take a snowmobile safety course. The course emphasizes safe and responsible snowmobile operation."
Hope this helps. Further information can be found on each of their respective websites.
Steve