To obtain a marriage dissolution in Minnesota, one or both spouses must reside in Minnesota for at least 180 days. If the residency requirement cannot be met, a legal separation may be done without 180 days residence.
Venue refers to the county where the proceeding takes place. As long as the 180-day residency requirement is met, it does not matter how long one or both spouses has/have resided in a certain county to proceed with the action in that county. So if the parties reside together, or reside in the same county, then the home county is the proper venue for the case.
If the parties reside in separate counties, then the case may proceed in either county. So the petitioning party may commence the action in their own home county, or in the other party’s home county. Once the action is commenced in one county, it is very unlikely to be transferred to a different county. That said, if the case is filed in one county by mistake (i.e., neither party resides in that county), then there is no proper basis for proceeding in the first county, and both courts (the one where the case was mistakenly filed, and the one where the case is properly filed) are likely to cooperate with the correction.
However, if the case is commenced in one county, either by mistake or intentionally, and there is a proper basis for the case to proceed in that county, and then there is an effort to move the case to a different county, the courts are not likely to accommodate the change, especially if one of the parties objects.