Since the only state without a seat belt law is New Hampshire, it will be in grey.
For the other 49, the law falls into the categories of ‘primary’ and ‘secondary’.
Primary means that the police can use it as a reason to pull you over and cite you.
Secondary means that police need to pull you over for something else and make note of it during the stop. (I.E. Pull you over for failure to signal and cite you additionally for not wearing a seat belt.)
As an advisory: Police cruisers and motorcycles now record audio and video as part of the traffic stop. Additionally, courts are more likely to side with the police officer when he says “I witnessed them buckling up as I was pulling over/as I approached the vehicle.”
Red: Primary states
Blue: Secondary states