As we know, the US Supreme Court in Shelley v. Kraemer, 334 U.S. 1 (1948), held that courts could not enforce racial restrictive covenants on real estate. The logic—seizing on the state action involved in court enforcement—always seemed a bit, um, leveraged to me, but few people at the time would have thought Congress had the power (even if it had the inclination) to ban such private contractual arrangements. Pondering this today, I suddenly wondered whether any states had already undertaken to ban such restrictive covenants. Googling has not proven terribly helpful so far.
If this link works, it will take you to a law review article: Lowe, Racial Restrictive Covenants, 1 Ala. L. Rev. (1948). On pp.24-25, this article indicates that court decisions in 19 states and the District of Columbia had held such covenants to be enforceable, and nowhere had they been squarely struck down. This seems to imply that no state had stepped in with legislation to outlaw them. The only reference I can see to an attempt at legislative action was a failed attempt by the city of Denver (see p.28)
That same article notes that presidential commissions under Hoover and Truman had recommended legislative elimination of racially restrictive covenants, although it does not specify whether they were referring to state or federal legislation. If you can track down any records from those commissions, they might include a discussion of state law as it then existed.