You will have to report all sources of income to the state of IL if you are still considered a full-year resident of Illinois, but you can claim a credit for taxes paid to Minnesota. It is possible that the credit for taxes paid to MN might not cover your entire tax liability for IL, so you may owe some tax to IL. File the form IL-1040 along with a Schedule CR (credit for taxes paid in other states).
Keep in mind: You do not have to be physically present in Illinois the entire year to be considered a full-year resident.
http://www.revenue.state.il.us/Individuals/StudentDefinitions.htm
You will also need to file a Minnesota tax return. Your residency status for MN depends on how many days you spent in MN.
http://www.revenue.state.mn.us/individuals/individ_income/Pages/Nonresidents.aspx
