State lines are the boundaries that separate one U.S. state from another. These lines are often marked by signs and can be found on maps, indicating where one state's laws and regulations begin and another's end. Each state has its own unique set of rules, which can affect everything from taxes to driving laws. Crossing state lines can have various implications, such as changes in legal jurisdiction or differences in public services. For example, when traveling from California to Nevada, a person may encounter different speed limits and tax rates. Understanding state lines is important for residents and travelers alike.