(A) Distribution of neurologists using Medicare data. In the Medicare data, there are 13,627 neurologists. The average density of neurologists is 22.3 (95% CI 20.6–24) per 100,000 Medicare beneficiaries, with a range from 9.7 (95% CI 9.2–10.2) in the 1st (low) quintile Hospital Referral Regions (HRRs), 2nd quintile HRRs: 14.2 (95% confidence interval [CI] 13.9–14.6), 3rd quintile HRRs: 19 (95% CI 18.6–19.4), 4th quintile HRRs: 25.5 (95% CI 24.8–26.1), and 5th (high) quintile HRRs: 43.1 (95% CI 37.6–48.5). (B) Distribution of neurologists using American Academy of Neurology (AAN) membership dataset. In the AAN membership dataset, there are 14,935 neurologists practicing in clinical settings. The average density of neurologists is 23 (95% CI 21–25) per 100,000 Medicare beneficiaries, with a range from 7.7 (95% CI 7.1–8.3) in the 1st (low) quintile HRRs, 2nd quintile HRRs: 12.6 (95% CI 12.3–13), 3rd quintile HRRs: 18.2 (95% CI 17.6–18.8), 4th quintile HRRs: 26.8 (95% CI 26–27.8), and 5th (high) quintile HRRs: 49.6 (95% CI 44.2–55.1).