Divorce, like marriage, is the province of the state governments, not the federal government. Divorce laws vary from state to state, but no-fault divorce on the grounds of "irreconcilable differences" is now available in all states. However, in recent years many states, including North Carolina and New York requires a one-year legal and physical separation prior to a formal divorce decree.

This legal requirement has led to the creation of a separate, somewhat ambiguous category of relationships - "separated". Once a more informal term used by individuals, it has now become a legal category designating someone who is neither married nor divorced.

Prior to the 1970s, divorcing spouses had to allege that the other spouse was guilty of a crime or sin like abandonment or adultery; when spouses simply could not get along, lawyers were forced to manufacture "uncontested" divorces. The no-fault divorce revolution began in 1969 in Indiana; South Dakota was the last state to allow no-fault divorce, in 1985.

State law provides for child support where children are involved, and sometimes for alimony. The median length for a marriage in the US today is 11 years with 90% of all divorces being settled out of court.