A complete and uniform classification of nonhighway use is not possible due to differences among the states as to what classes of nonhighway use are eligible for exemptions or refunds and because states do not apply for all refunds. All nonhighway uses of gasoline were estimated by the U.S. Department of Transportation, Federal Highway Administration or data were obtained from other sources. These estimates may not be comparable to data for prior years due to revised estimation procedures.
All data are subject to review and revision.
Numbers may not add to totals due to rounding.