The division of marital property after a divorce will generally depend on whether or not you live in a community property state. The best way to determine whether your state is a community property state is to talk to a local attorney who can tell you what the law is and who can help you understand how that affects your situation.
Community property states consider nearly all property obtained after the marriage as equally owned by both spouses. As a result, the property will generally be equally split after the divorce. Absent community property statutes, it's typically up to the court to divide marital property between both parties. In either case, courts will normally accept a property division agreement if the spouses can create their own.