Divorce is something each state manages within its own borders. Even though other states will recognize your divorce just as they would recognize your marriage performed in Illinois.
Because divorce is a legal process, you must get a divorce in a state in which you meet the residency requirements.
Residency requirements in Illinois
According to the Illinois State Bar Association, there is no residency requirement in the state. However, a judge cannot grant a divorce unless one party has lived in the state for at least 90 days. In addition, you must file your petition in the county in which you live or in which your spouse lives.
You should note that residency will impact other aspects of your divorce. Since you must file in the county in which or your spouse lives, you must also pay the fee for that county. Each county sets its own fees, so they may vary greatly. Do note that if you cannot afford the fee, you can file for a waiver with the court.
Another place in which your residency may impact your divorce is when it comes to child custody. The court will consider where you live in respect to your spouse when determining custody arrangements. If you move out of state or a long distance from where you lived during the marriage, it could impact your parenting time.
The court likes to provide children with stability and avoid too much change to their normal routines. If they would have to move with one parent but not the other, it can influence decisions.