Most states have titling and registration laws that require residents to title and register their cars in the state—and for new residents of the state to do so within some period of time, such as 30 days. Some states require titled cars to pass a comprehensive safety inspection. And some states also require cars owned by residents of certain counties to pass an emissions test/inspection designed to improve air quality in more densely populated counties.
In Wyoming, residents are required to title and register their vehicles with the state. New residents must title and register their vehicles within 30 days of establishing residency. Wyoming does not have a statewide vehicle safety inspection program, so vehicles are not required to pass a comprehensive safety inspection for titling or registration purposes. However, Wyoming does require emissions testing for vehicles registered in Laramie County, which includes the city of Cheyenne. This emissions testing is part of the state's effort to comply with federal air quality standards and is designed to reduce air pollution in this more densely populated area. Residents in other counties are not subject to emissions testing requirements.