Snocross (also snowcross) is a racing sport involving racing specialized high performance snowmobiles on natural or artificially-made tracks consisting of tight turns, banked corners, steep jumps and obstacles. Riders race at speed of up to 60 miles per hour (96 kilometres per hour). Jumps are up to tall, so riders travel up to before they touch the ground. According to the World Snowmobile Association which governs snocross, watercross, and hillcross racing, snocross is the most popular form of snowmobile racing. Snocross was derived from the sport of motocross. The name is a portmanteau of the words "snowmobile" and "motocross". The sport uses a snowmobile instead of a motorcycle, and a snow/ice surface instead of dirt. The snow/ice surface which is either natural or man-made. Tracks are generally located in higher latitudes in the Northern Hemisphere since temperatures below freezing are required to maintain the frozen track surface. Motorcycle riders in motocross and supercross frequently compete in snocross in the winter. Snocross became an event at the X Games in 1998. X Games is a popular gathering place for some snow-related sports in the United States. The course at the first snocross event at the X Games resembled a motocross course; it was significantly longer than courses are now. It had deeper holes and higher jumps that are now filled in with snow. Equipment The snowmobiles vary significantly depending on their class. Sanctioning bodies are governed by International Snowmobile Racing (ISR) rules. Drivers are required to wear a helmet with a minimum of 50% International (Blaze) Orange. (Rule of thumb, a credit card placed anywhere on the helmet must contact orange), racing suit (must have a minimum of 144 square inches of orange on front and back), gloves, goggles/eye protection, leather boots, shin guards, elbow pads, neck braces, knee guards, and upper body protection (Motocross vests are NOT legal for Snocross. Hearing protection is often required in non-stock classes. Event Races start with the drivers forming a line abreast at the start line. The event begins with either a drop of a green flag by the starter or by the starter turning on a light. Like other sports derived from cross country running, the winner is often the rider who has the best holeshot. The event may be stopped for a dangerous condition. The snowmobiles are lined up for the restart by their position in the race, with the drivers involved