<p>The escalating mental health crisis in the USA has left over fifty percent of adults with a mental illness without mental health services. Federal mental health parity legislation addresses financial barriers to mental healthcare by requiring that insurance coverage for mental health services is equivalent to coverage for other medical services. Using data from the top ten and bottom ten states ranked by per capita State Mental Health Agency expenditures, this paper examines the impact of parity implementation and enforcement on three system-level access to care measures: (1) mental health workforce availability, (2) percent of state population living in a mental health shortage area, and (3) percent of total health expenditure spent on mental health by state agencies. As hypothesized, the top ten states had more comprehensive parity implementation and enforcement and a larger allocation of total health expenditures to mental health (<i>p</i> = 0.0002). The other two measures did not show a significant difference but trended in the direction of greater workforce availability (<i>p</i> = 0.11) and fewer residents living in mental health provider shortage areas (<i>p</i> = 0.054) among the top ten states compared to the bottom ten states. Using the scope of mental health parity alone, all three access-to-care measures were significantly better among states with comprehensive parity compared to states without comprehensive parity. These findings highlight the critical roles of financial investment, policy prioritization, and enhanced mental health infrastructure in addressing access to mental healthcare.</p>