6.4

• urban system - an interconnected set of cities that interact on the regional, national, and global scale
• rank-size rule - the sizes of cities within a region may develop
• higher-order services - expensive; need a large number of people to support; only occasionally utilized
• lower order services - less expensive; require a small population to support, used more on a daily/ weekly basis
• primacy/primate city - when the largest city in an urban system is more than twice as large as the next largest city
• gravity model - larger and closer places will have more interactions than places that are smaller and farther from eachother
• central place theory - explain the distribution of cities of different sizes across a region
• central place - a location where people go to buy and sell goods and services, such as a market
• Market area


  Zone that contains people who will purchase goods or services
• Higher-order services

  • Have larger market areas than lower-order services
• Hexagonal hinterlands

  Shape chosen by Christaller to depict market areas as a compromise between a square (where people in corners are farther from the central place) and a circle (with overlapping areas of service)
• Nesting hexagons


  Allowed for central places of different sizes to distribute themselves in a clean pattern across the region
• threshold - size of population necessary for any part service to exist and remain profitable
• range - the distance people will travel to obtain specific goods or services