Neighborhoods in the City of Baltimore are officially divided into nine geographical regions: North, Northeast, East, Southeast, South, Southwest, West, Northwest, and Central, with each district patrolled by a respective precinct of the Baltimore Police Department. Charles Street down to Hanover Street and Ritchie Highway serve as the east-west dividing line and Eastern Avenue to Route 40 as the north-south dividing line. However, Baltimore Street is north-south dividing line for the U.S. Postal Service. It is not uncommon for locals to divide the city simply by East or West Baltimore, using Charles Street or I-83 as a dividing line.