region vs tract

region

noun
  • Any considerable and connected part of a space or surface; specifically, a tract of land or sea of considerable but indefinite extent; a country; a district; in a broad sense, a place without special reference to location or extent but viewed as an entity for geographical, social or cultural reasons. 

  • A subnational region of Chile; equivalent to province. 

  • An administrative subdivision of the European Union. 

  • A subprovincial region of Quebec; the primary level subdivision; a prefecture. 

  • The inhabitants of a region or district of a country. 

  • A place in or a part of the body in any way indicated. 

  • Such a division of the city of Rome and of the territory about Rome, of which the number varied at different times; a district, quarter, or ward. 

tract

noun
  • An area or expanse. 

  • Part of the proper of the liturgical celebration of the Eucharist for many Christian denominations, used instead of the alleluia during Lenten or pre-Lenten seasons, in a Requiem Mass, and on a few other penitential occasions. 

  • A series of connected body organs, such as the digestive tract. 

  • A commentator's view or perspective on a subject. 

  • Continued or protracted duration, length, extent 

  • A brief treatise or discourse on a subject. 

  • A small booklet such as a pamphlet, often for promotional or informational uses. 

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