Mowing the highway right-of-way (ROW) is important for the safety of roadway users and for maintaining highway infrastructure. This paper reports fuel usage and exhaust emission rates from on-board measurements of 12 diesel tractors operated in real-world mowing conditions by the New York State Department of Transportation. The operating conditions and the mower type were the dominant variables determining area-based fuel consumption requirements. Fuel consumption rates were consistent across the different conventional tractor mowing equipment (sickle bar, flail, and rotary mowers), with an average fuel-consumption ± standard deviation of 5.1 ± 2.3 kg-fuel/ha roadside area mowed. Mowing over the guiderails, using a large tractor and a small cutting head, demanded an average fuel-consumption ± standard deviation of 44 ± 15 kg-fuel/ha, which is almost ten times as much fuel per unit area than other conventional mowing activities. Fuel-based emission factors (g-emission/kg-fuel) better reflect the difference across tractor technologies in terms of emission rates of criteria pollutants [e.g., carbon monoxide (CO), hydrocarbon (HC), nitrogen oxide (NO), and particulate matter (PM)]. Fuel-based emission factors measured from the in-use tractors compared quite well with the U.S. Environmental Protection Agency (U.S. EPA) NONROAD emission factors and confirmed the effectiveness of the U.S. EPA nonroad standards to lower emissions from agricultural tractors. The analysis presents methods for estimating fuel usage and emissions from mowing activities and makes observations about mitigating the environmental impact of mowing activities. Study results can assist in better procurement of appropriate size tractors to yield both fuel savings and emissions benefits.