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 South Dakota, residents are required to title and register their vehicles with the South Dakota Department of Motor Vehicles (DMV). New residents must title and register their vehicles within 90 days of becoming a resident of the state. South Dakota does not require a state-wide vehicle safety inspection for passenger vehicles. However, commercial vehicles must pass an annual safety inspection. As for emissions testing, South Dakota does not require vehicles to undergo emissions testing, regardless of the county of residence. This means that residents of more densely populated counties are not subject to different requirements than those in less populated areas when it comes to vehicle emissions.