According to the Minnesota M-1 Instructions:
A Minnesota Resident is an individual that is domiciled in Minnesota. If you are a resident of another state, you may still be considered a Minnesota resident if you occupy an abode suitable for year round use and spend at least 183 days in Minnesota during the tax year.
A Nonresident of Minnesota is an individual that is a resident of another state and has spent less than 183 days in Minnesota.
A Part-Year Resident is an individual that has moved into or out of Minnesota during the year.
If one spouse is a resident and the other is not, file a joint return.
For more information: