The law of retail gravitation (LRG) and the economic law of market are
as (LMA) both seek to define the market-area boundary between two comp
eting centres. Each law is reviewed and then characterized in terms of
the principal dimensions of the market-area boundary. It is shown tha
t under certain conditions the two laws correspond exactly, so that th
e LMA is able to lend some economic support for the LRG. If, however,
approximate correspondence between the laws is permitted, this support
is considerably greater. The two laws are also viewed within the broa
der framework of an hierarchically structured urban system. Exact corr
espondence between the laws is again possible under particular circums
tances, but the descriptive capacity of the LMA is greatly increased w
hen approximation is allowed. Finally, consideration is given to the p
ossibility of modifying the LMA in order to take account of the effect
s of nonprice competition.