A sheriff is the top-ranking officer in a county police force. Unlike police in a city or town, the sheriff is an elected official.
In most states, the sheriff serves a four-year term, and she oversees a department of police officers. A sheriff's job varies from state to state, but it generally includes enforcing the law, making arrests within the county, traffic control, prisoner transportation, and crime investigation. The Old English root word is scirgerefa, "representative of royal authority in a shire." Sheriff has been used in the United States since the 1600's.