Medicaid is the largest payer for publicly funded contraception, serving millions of women across the United States. However, relatively little is known about the extent to which effective contraceptive services vary geographically for Medicaid recipients. This study used national Medicaid claims to assess county-level variation in rates of provision of the most or moderately effective methods of contraception and provision of long-acting reversible contraception (LARC) across forty states and Washington, D.C., in 2018. County-level rates of most or moderately effective contraceptive use varied almost fourfold across states, from a low of 10.8 percent to a high of 44.4 percent. Rates of LARC provision varied almost tenfold, from a low of 1.0 percent to a high of 9.6 percent. Despite the fact that contraception is a core benefit within Medicaid, access and use vary substantially across and within states. Medicaid agencies have a variety of options to ensure that people have access to a choice of the full range of contraceptive methods, including removing or loosening utilization controls, incorporating quality metrics or value-based payments into contraceptive services, and adjusting reimbursement to remove barriers to the clinical provision of LARC.