This is a little known fact: Although you probably hear about common law marriage a lot, only a handful of states even allow common law marriage anymore, and the number that do allow it keeps decreasing as those states realize common law marriage just ends up causing more problems than it is worth.
To be exact, as of 2020, only eight states still allow common law marriages to be formed in them. An additional five states allow common law marriages, but only if those marriages were formed before a specific date (meaning new common law marriages are allowed).
However, all 50 states must recognize common law marriage validly created in other states that allow them. So if you formed a common law marriage in a state listed below and then move to another state, your new state will be forced to recognize your marriage as valid.
The following states allow common law marriage:
Signing an affidavit of marriage will help ensure your common law marriage is legally valid. In it, both partners swear that they are married to one another. Again, this will only work in states that allow common law marriages.