In the United States, rural and low-income communities have difficulty attracting and retaining physicians, potentially adversely impacting health outcomes. With a limited supply of physicians completing medical school at US universities, foreign-born and educated physicians provide a potential source of supply in underserved areas. Although nearly a quarter of medical residents in US hospitals received their medical degrees abroad, the terms of the commonly used J-1 visa require a return to the home country for two years, which may limit the capacity of international medical graduates (IMGs) to pursue employment in the US market. Our analysis examines the extent to which reducing visa barriers impacts the supply of physicians at state and local levels, particularly in areas designated as medically underserved. The Conrad 30 Visa Waiver program gives states the opportunity to attract foreign IMGs to practice in underserved areas by waiving the two-year home residency requirement for those with J-1 visas and providing a path to obtaining US citizenship. Changes in the federal limit on the number of waivers per state, combined with variations in the state-level restrictions on eligible specialties and geographies in which physicians can work, provide evidence of the role of visa restrictions in limiting the supply of doctors. We find that the expansion of the cap on visa waivers increased the supply of IMGs in states impacted by the cap lift. There is little evidence of reductions in US-trained doctors in states where IMGs increases were the largest, suggesting little evidence for crowding out. Health Professional Shortage Areas (HPSAs) in states with fewer restrictions on the program had relatively more IMGs but no fewer US-trained doctors. Importantly, HPSAs in states with less restriction to the program also had relatively lower early mortality rates and lower COVID-19 death rates.