If I want a divorce, what state do I have to file in?

Any State with jurisdiction. You can file here if you have lived here for 6 weeks, but depending on facts you do not recite, the court may, or may not, have jurisdiction to make every kind of ruling you want or need.

If there are children involved, you need to file where the children have lived the past 6 months. If there are no children, but there is real property, then you should file where the real property is located. If there are no children, and there is no real property, then you can file in either Nevada or Maryland. However, if you file in Nevada, your spouse may be able to claim a lack of personal jurisdiction and/or an inconvenient forum. You may wish to discuss this with your spouse. If you can agree to the terms of a divorce, you can get it done much faster in Nevada (as we allow "no fault" divorces).