The commerce clause (Article I, Section 8, Clause 3) in the United States Constitution gives the federal government the ability "to regulate Commerce with foreign Nations, and among the several States, and with the Indian Tribes."
Although state governments have criticized the clause on several occasions—particularly due to their view that it gives the federal government too much power over state economies—the clause had the unintended benefit of outlawing racial discrimination in restaurants and other public facilities.
During the Civil Rights era, the commerce clause protected African American patrons from being banned from establishments by racist business owners. The United States Supreme Court helped secure the ability of the federal government to implement the commerce clause in states that had Jim Crow laws.
Without the commerce clause, state governments that practiced institutional racism could allow and protect white business owners in targeting African American customers.