The rank size rule attempts to establish a numerical relationship between population sizes of settlements within a country or region. It ranks settlements by population size, with the largest first. It assumes the second largest settlement will be half the population of the largest, the third largest a third, and so on. While variations often occur, it provides a model for comparing city population distributions. Exceptions include primate cities, where one city dominates population size, and binary distributions, where two cities are of almost equal size.

1. Rank Size Rule
Settlement

2. Learning outcomes
 To
understand what the rank Size
rule is and the pattern that it tries to
outline

3. Rank Size Rule
 This
is an attempt to find a numerical
relationship between population size
of settlements within an area such as
a country or county
 Settlements are ranked in
descending order of population size,
with the largest city first

4. Assumptions
 The
2nd ranked city will have 1/2 the
population of the 1st
 The 3rd ranked city will have 1/3
population of the 1st
 The 4th ranked city will have a ¼
population of the 1st ranked city

5. Example
 The
largest city has a population of
1,000,000
 The 2nd largest city: 1,000,000/2=
500,000
 The 3rd city: 1,000,000/3= 333,333
 The 4th city: 1,000,000/4= 250,000
 And so on….

6. Formula
This allows us to express the rank size rule
as:
 Pn= Pl /n (or R)

Pn= The population of the City
 Pl= The population of the largest city
 N (or R)= The rank size of the city


See graph Page 404/405 Brazil e.g.

7. Variations from the Rank Size Rule
 It
is rare to find a close correlation
between the city size of a country
and the rank size rule

8. Primate City
 This
is found where the largest city
(often the capital) completely
dominates a country or region
 The population size will be many
times greater than that of the 2nd or
3rd city

9. Example of Primate City: Buenos
Aires
 Populations
in thousands:
 Buenos Aires: 10,990
 Cordoba:
1198
 Rosario:
1096
 Mendoza:
775
 La Plata:
640
 San Miguel de Tucuman: 622

10. Binary Distribution
 Occurs
where there are 2 very large
cities of almost equal size within the
same country. One may be the
capital and the other a major port or
industrial centre
 Examples: Spain- Barcelona and
Madrid

11. Exceptions to the rule
Rank size rule is more likely to operate in
a country that is developed or urbanised
for a long time
 Large in size
 Stable economic and political organisation
 Primate distribution is likely to occur in
countries that are small, less developed
and only recently urbanised
