Would that marriage laws, which vary greatly from one state to the next, were as simple as a yes or no. As a general rule, the law that governs the validity of a marriage is determined at the time and place of the claimed marriage. Illinois, according to Wikipedia, does not recognize "common-law," meaning non-ceremonial, marriage. However, a couple now living in Illinois who previously lived in a state that does, and their relationship at that time met the requirements for marriage at common law, would be married. That marriage, commenced under the different law of another state, would be recognized in Illinoise. Typically, the proof of the marriage is compicated when one party denies the marriage.
For precise and focused advice regarding your rights, married or as unmarried co-parents, nothing short of a consultation with an experienced family law practitioner in your area will meet your needs.
Best wishes for a favorable outcome, and please remember to designate a best answer.
This answer is offered as a public service for general information only and may not be relied upon as legal advice.
No, Illinois does not recognize common law marriage. Only a small minority of states recognize common law marriages.
The information provided here should not be construed to be formal legal advice. The provision of this general advice does not create a lawyer-client relationship. Persons with legal questions are encouraged to seek independent counsel for advice regarding their individual legal issues.
You have very few rights aside from child support, and there has to be an establishgment of paternity before you can even get that. If I recall correctly, Illinois has not recognized common law marriage since 1903. Get a lawyer.