Health services Literature suggests that geographic information systems (GIS) are useful policy evaluation tools when policy success is dependent on location. Nursing workforce distribution is an inherently Local issue and nursing shortages present serious concerns for local, state and national governments. In 1991, Missouri enacted a nurse recruitment and retention policy targeting underserved (HPSA-designated) counties. Following Institutional Review Board approval, policy effectiveness was explored using a combination of GIS data visualization, spatial and classic statistics. Results of both data visualization and statistical methods do not demonstrate an expected trend of decreasing group differences between HPSA and non-HPSA-designated counties over time. Only two of the five time periods studied had significant group differences. Between 1993 and 1995, the toss in nurse to population ratios in HPSA counties was significant (U = 1020, p < 0.001); however, between 1999 and 2001, the growth in nurse to population ratio changes in HPSA counties was significant (U = 1032, p = 0.001). The GIS data visualization and statistical techniques performed suggest that current policy definitions of underserved areas may not be effective in defining areas of nursing shortages and the existing policy implementation may not be achieving the stated goals. (c) 2005 Elsevier Ireland Ltd. All rights reserved.