Relationship between trauma center patient volume (TCV) and mortality remains inconclusive. Our aim was to determine the relationship between TCVs and observed/expected (O/E) all-cause mortality. This is the first study to evaluate the relationship between trauma center (TC) volumes and O/E all-cause mortality with no exclusion. Review of prospectively collected data from 94 TCs using the National Sample Program from the National Trauma Data Bank 2013. TCs were stratified into five groups based on TCV: <701, 701 to 1200, 1201 to 1700, 1701 to 2200, and >2200 yearly patient encounters. Chi-square and coefficient of determination were used for data analysis with a statistical significance defined as P-value < 0.05. A total of 139,324 trauma patients with blunt and penetrating injuries were evaluated from the National Sample Program. Of which, 63.6 per cent were male, 70.6 per cent white, and the average age was 41 years. The data were stratified by TCV into five groups with average O/Es ranging from 0.69 to 0.86 (P > 0.05). The coefficient of determination between TCV and O/E was r = 0.14 and r2 = 0.02. When controlling for Injury Severity Score, the correlation between mechanism of injury (blunt vs penetrating) and O/E mortality was r = -0.025. The group with the lowest average volumes had statistically significantly worse outcomes than the group with next higher volumes and also worse than the group with the highest volumes (Group 5, P = 0.04). Higher TC volumes correlated with higher injury severity and lower O/E mortality.