The aim of this study was to estimate the distance Mississippi patients must travel to access hospital-based emergency rooms (ERs) and to determine whether an association exists between geographic distance and ER utilization. To that end, great circle distances between Census Block Group Centroid Points and 89 hospitals with emergency departments were calculated for the State of Mississippi. Data on the socio-demographic characteristics of each block group came from the 2000 US Census data. Logistic regression analyses were conducted to test if there was any association between ER utilization and travel distance. Compared to the national benchmark of 35.7%, more than one in two (56.7%), or 1,612,762 Mississippians visited ERs in 2003 with an estimated 6.1 miles per person annual travel for this purpose. The majority of the target population (54.9%) was found to live within 5 miles of hospitals with ERs. Logistic analyses revealed that block groups associated with less miles traveled to hospitals with ERs had a higher proportion of African Americans, impoverished people, female householders, people with more than 12 years education, people older than 65 years, people with high median house values, and people without employment. Twenty-nine of the 89 hospitals (33%) providing ER care in Mississippi were found to be in areas with above-average ER utilization rates. These hospitals served a smaller geographical area (28% of the total) but had a greater proportion of visitors (57%) and served a higher percentage (37%) of the state population. People in areas served by the less utilized ERs traveled more miles to be cared for (7.1 miles vs 5.4 miles; p<0.0001). Logistic regression analysis revealed that shorter distances were associated with increased use of the ERs, even after controlling for socio-demographic factors. The conclusion is that Mississippi ERs are typically located in block groups with higher percentages of disadvantaged residents and that people in these areas are more likely to utilize ER services. Our data suggest that the geographical distance has an impact on ER utilization, especially by reducing utilization in disadvantaged block group areas. Disadvantaged persons living near ER hospitals (<5 miles) were found to be more likely to utilize the ER services. Geographic distance should therefore be considered when planning state-wide ER programmes for disadvantaged populations.