Borough vs District

Borough

name
  • The area, properly called Southwark, just south of London Bridge, which is at the north end of Borough High Street (OS grid ref TQ3279). 

District

name
  • The District Line of the London Underground, originally known as the District Railway. 

  • The District of Columbia, the federal district of the United States. 

  • Any of numerous governmental districts. 

How often have the words Borough and District occurred in a corpus of books? (source: Google Ngram Viewer )