Aggregate Demand Index (ADI) survey results were used to describe the severity of the pharmacist shortage at the national and state levels and by practice site and impact on the U.S. population. Time-series analysis was used to characterize national and state trends in the ADI from September 1999 through September 2003. The time trends for the distribution of ratings and the demand index by practice site were also examined. Historical data about retail prescriptions filled and related growth rates were compiled and compared. ADI survey results were also compared with data from other surveys. Over time, ADI data demonstrated a continuing national pharmacist shortage, as the ability to fill pharmacist vacancies was rated at least moderately difficult. A very slight downward trend in severity (slope = -0.008) was observed. Other survey series had similar findings. States with the most severe shortage levels tended to have large populations, while those with the lowest levels tended to have smaller populations. More states improved than worsened the severity of their shortage, with 30 states maintaining the same ADI rating. Although there was a high correlation between the retail prescription growth rate and the ADI (r = 0.84), there was a much greater decrease in prescription growth (73%) than ADI levels (6.5%). There was a sustained unmet demand for pharmacists throughout the United States from September 1999 through September 2003. More states moved toward having an adequate supply of pharmacists than toward having a more severe shortage of pharmacists, but the national ADI suggests that the system remains stressed.