Medicaid was created by Congress in 1965 under Title XIX of the Social Security Act. The federal government sets minimum standards and pays a share of each state's costs — ranging from 50% to 77% depending on the state's wealth. States administer the programs and can expand eligibility above the federal floor. The federal government's share is called the Federal Medical Assistance Percentage (FMAP). Because states receive reimbursements after paying providers, the federal government can withhold those payments to exert pressure on state compliance, a contested but legally available tool.