Final answer:
Highway safety laws are regulated by state governments through their reserved powers. This allows each state to make its own laws concerning highway safety, such as laws against cellphone use while driving and DUI regulations.
Step-by-step explanation:
Highway safety laws are predominantly governed and enforced by state governments in the United States, drawing authority from their reserved powers. Reserved powers, not expressly delegated to the federal government by the Constitution, empower states to establish and regulate their own highway safety laws. This includes the formulation and enforcement of rules related to cellphone use while driving, speed limits, seatbelt requirements, and DUI regulations. The autonomy granted by reserved powers allows states to tailor highway safety regulations to their specific needs and preferences.
Additionally, state governments shoulder the responsibility for constructing and maintaining the extensive network of interstates and highways, reflecting a comprehensive jurisdiction over various facets of highway safety. This decentralized approach underscores the flexibility for states to address unique traffic safety challenges and preferences while ensuring a consistent focus on road safety across the nation.