The district encompasses all of the county 's 1,300 square miles ( 3,400 km ) .
The district serves the area 's 15 cities , 1.8 million residents and more than 200,000 commuters .
The district encompasses all of the county 's 1,300 square miles ( 3,400 km ) and serves the area 's 15 cities , 1.8 million residents and more than 200,000 commuters .