Amends the Illinois Vehicle Code. Changes the definition of "all-terrain vehicle" to mean certain vehicles that are 74 (instead of 50) inches or less in width. Permits the operation of all-terrain vehicles meeting certain criteria on any street, roadway, or highway in this State, unless the highway is an interstate system or is near a grade-separated portion of the highway. Provides that an all-terrain vehicle may be registered in the same manner as provided for snowmobiles and shall comply with the registration, fees, insurance, and other requirements for snowmobiles under the Snowmobile Registration and Safety Act. Outlines the vehicle equipment requirements for the operation of an all-terrain vehicle on a roadway. Makes other changes.