Guidelines published in 2001 recommended 1 regional adult congenital heart disease (ACHD) center per 3 to 10 million population. Our objective was to determine if published guidelines on the numbers of regional ACHD centers are sufficient to meet the needs of adults with congenital heart disease in the general population. Population data were examined to evaluate the recommendations for the number of regional centers. We extrapolated a population prevalence of 4.09 per 1,000 adults corresponding to 847,896 and 87,375 patients with ACHD in the United States and Canada, respectively. We reviewed the information currently available on the numbers of ACHD facilities of any kind indexed to continental populations. We examined the distribution of disease and health services in pediatric and adult populations and examined the evidence for pressure points during the transition process. Published data on 6 of the largest regional ACHD centers were used to model regional center care. We reviewed determinants and recommendations for follow-up in regional centers. We explore 3 scenarios of referral patterns to regional centers, examining their impact of the number of centers required per country population. In conclusion, we demonstrate that 1 regional ACHD center for a population of 2.0 million adults appears to be closer to what is required for improving access to specialized care for patients with ACHD in the United States and Canada.