According to the United States Department of Transportation (USDOT), more than 3.1 billion tons of hazardous materials (HazMat) are shipped within the United States annually. This averages to about 800,000 individual shipments of HazMat per day, of which 300,000 are shipments of petroleum/flammable-combustible liquids. This paper presents a temporal trend study (1995-2004) of 2145 HazMat incidents occurring through the transportation of flammable/combustible liquids. The study also correlates between HazMat incidents and distances between shipment origin and incident location. These distances attained through great circle calculations since the data compilation did not allow for the identification of specific routes taken in commodity transport. Findings of this study illustrate a bimodal distribution of frequency as a function of the logarithm of the Distance with first mode (less than 105 miles) mean of 24 [km] and second mode mean of 1061 [km]. Additionally, transport phase introduced no significance to the distribution of frequencies. (C) 2009 Elsevier Ltd. All rights reserved.