ENGLISH :
Aims This study investigated interstate substance abuse treatment needs and access in the USA. Design After assessing the validity of recently developed survey and indicator measures, the study analysed the geographic distribution and nature of state substance abuse treatment needs. Substance abuse treatment utilization index scores were regressed on the need measurements to identify differences among state populations in treatment access. Findings The interstate substance abuse treatment need measures had evidence of reliability and construct validity. Treatment needs clustered in stable, distinct geographic patterns. The most severe problems, primarily reflecting alcoholism, were in the west. Drug and alcohol substance use disorders and related problems were not significantly correlated at this level of aggregation. There was evidence of regionalization of the drug-of choice mix in treatment admissions. Only 21% of the variations in state treatment utilization rates stemmed from the prevalence of substance use disorders and related problems. The biggest treatment gaps were in the south and south-west, regions with large minority populations. Conclusions Development of interstate survey and indicator measures of treatment needs has created new opportunities to broaden our understanding of substance abuse epidemiology and treatment access in the USA. The nature and severity of drug and alcohol problems vary from state to state, but the interstate disparities in treatment services remain even after variations in treatment need have been discounted. Further research is needed to understand the causes of these differences in treatment access. (Author' s abstract)