According to the Missouri website:
A Resident of Missouri is an individual that is domiciled in Missouri. If an individual is not domiciled in Missouri but has permanent living arrangements in Missouri and spends more than 183 days in Missouri, they are considered Missouri residents.
A Nonresident of Missouri is an individual that is not a resident of Missouri (domiciled elsewhere). An individual that is domiciled in Missouri but: (a) does not maintain a permanent place of abode in Missouri, (b) maintains a permanent place of abode elsewhere and (c) spends no more than 30 days of the tax year in Missouri is considered a nonresident.
A Part-Year Resident is an individual that has moved into or out of Missouri during the tax year.
If one spouse is a resident and the other is not, you must file your state return using the same status as you filed your federal return.
For more information, see