The secondary trade area includes the less frequent shoppers within 10-30 minutes driving distance of the centre. A neighbourhood planned shopping centre expects to attract about 65-75% of the available expenditure on food in the PTA but only about 20% in the STA. The STA is more subject to competition from rival centres particularly nearby regionals. Therefore, the customer population in the STA is less reliable than those in the PTA. These are the "rat" customers in the Whiteman Smith case.

See goodwill

See primary trade area