District of Columbia vs United States of America

District of Columbia

name
  • The federal capital region of the United States of America. The City of Washington used to be a municipality within the District of Columbia until 1871, when two entities were merged. For this reason, the district is also generally known as Washington, D.C. 

United States of America

name
  • A country in North America, stretching from the Atlantic to the Pacific Ocean, and including Alaska, Hawaii, and several territories. 

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