Snowmobiles are used for snow travel. A rubber track helps to propel the craft while a ski in front helps to steer the machine. Speeds in excess of 100 mph are possible with the fastest snowmobiles with some enthusiasts claim they can push their machines to do 125-135 mph.

There are four major snowmobile manufacturers—Arctic Cat, Yamaha, Polaris and Bombardier. In 2004, there were 109,750 snowmobiles sold in the U.S., and 48,556 snowmobiles sold in Canada. There are approximately 1.77 million registered snowmobiles in the US (less than 0.5% of the population) and 557,000 registered snowmobiles in Canada. The states with the largest number of registered snowmobiles are Michigan 392,308, Wisconsin 220,000, and Minnesota 272,600.

The average suggested retail price of a new snowmobile sold in 2004 was $6,550. According to the International Snowmobile Manufacturers Association, the average age of a snowmobile owner is 41 years old with an average annual income of $70,000.

Snowmobiles may weigh up to 600 pounds. Depending on use snowmobiles are divided into broad categories including performance, mountain, touring, deep snow and sport utility.

Environmental Impacts

Snowmobiles are significant sources of air pollution. Snowmobiles emit carbon monoxide (CO), hydrocarbons (HC), and particulate matter (PM), as well as a variety of gases classified as "toxic air pollutants," including benzene, 1,3-Butadiene, formaldehyde, and acetaldehyde. Though nearly 16 times as many cars enter Yellowstone National Park each year, winter snowmobile use contributes to 90% of the total hydrocarbon emissions. Recently snowmobile manufacturers have developed four stroke (instead of the standard 2 stroke) engines that they claim are quieter and have fewer emissions. However, many enthusiasts still prefer the 2 stroke engine since it is considered to be superior in terms of power for weight and uses fuel more efficiently than a 4 stroke engine.

In February 2003, a coalition of public health organizations, including the American Cancer Society and Physicians for Social Responsibility, urged the Park Service to issue warnings to Yellowstone park visitors about the health risks associated with exposure to fine particulate matter found in snowmobile exhaust. These health professionals took this action after the Service issued paper masks to rangers working throughout the Park as a stop-gap measure designed to reduce their exposure to particulate pollution.

Noise pollution is another way that snowmobiles assault the public commons. The snarl of these machines can be heard for up to 3 miles either side of a trail, meaning that noise pollution may affect a six mile wide corridor. Up close, the constant whine of snowmachines can cause hearing loss and damage. Studies in 1999-2000 showed that kiosk workers and patrol rangers in Yellowstone were subjected to noise levels exceeding OSHA standards. Excessive noise levels can result in permanent hearing loss and can also raise blood pressure. Studies have shown hearing loss for persons subjected to 73 decibels of noise for 8 hours per day for 40 years, or when subjected to 85 decibels over a shorter number of years. Kiosk workers have been exposed to average noise levels of 88 decibels over an 8-hour work day, and a February 2000 study showed patrol rangers exposed to 93 decibel levels.

But the negative effects are not limited to humans. Snowmobiles damage the landscape and wildlife. For example, researchers found that 78% of saplings in an area were damaged with "nearly 27% of them seriously enough to cause a high probability of death” after being run over by a snowmobile only once."

Research in Alaska demonstrates that snowmobiles compact fragile tundra and permafrost ecosystems, cause permafrost to melt prematurely and generally increase soil temperatures.

More importantly, snowmobiles negatively impact winter wildlife through stress. Snowmobiles can displace animals from preferred foraging areas, force them to deplete stored energy reserves.Wildlife already stressed by limited food, cold temperatures and snow find any losses due to outside pressures such as snowmobile use can push them over the lethal limit.

Researchers have documented how snow compaction that accompanies significant snowmobile use can kills small mammals that live beneath the snow. Eliminating these animals has adverse consequences up the food chain, particularly on birds of prey.(Rongstad, Research Needs on Environmental Impacts of Snowmobiles, 1980; Brander, Ecological Impacts of Off-Road Vehicles, 1974)

Water quality impacts resulting from snowmobile use has not been studied as well-studied as air quality impacts, but snowpack samples near heavily traveled snowmobile trails have been correlated with elevated levels of ammonium, sulfate, benzene, and other carbon compounds from gasoline combustion, raising concerns about water quality.