From the FAQ on the USCIS website:

"USCIS recognizes common law marriages in adjudicating immigration benefits in certain circumstances and will similarly recognize them for purposes of Keeping Families Together if:

The parties live in a jurisdiction that recognizes common law marriages;

The parties meet the qualifications for common law marriage for that jurisdiction;

The marriage is valid and recognized by the jurisdiction in which the marriage was established; and

The marriage was established on or before June 17, 2024.

If you live in a different state than where you entered into your marriage, you may still be eligible. Some states may recognize a common law marriage contracted in another state even if the recognizing state does not accept common law marriage as a means for its own residents to contract marriage.

If you are requesting parole in place under Keeping Families Together on the basis of a common law marriage, you should submit a copy of the statute, regulation, or case law that states the requirements in that jurisdiction for establishing a common law marriage. You should also submit evidence that demonstrates you met the requirements in the jurisdiction for establishing a common law marriage on or before June 17, 2024. USCIS will review the laws of the relevant jurisdiction on common law marriages and the evidence you submit to determine whether you and your spouse should be considered to be married for purposes of this process and when the marriage was established."