As Philadelphia grew from a small town into a city in the first half of the eighteenth century, it became an increasingly important marketing centre for a vast and growing agricultural hinterland. Market days saw the crowded city even more crowded, as fanners from within a radius of 24 or more kilometres brought their sheep, cows, pigs, vegetables, cider, and other products for direct sale to the townspeople. The High Street Market was continuously enlarged throughout the period until 1736 when it reached from Front Street to Third. By 1745, New Market was opened on Second Street between Pine and Cedar. The next year the Callowhill Market began operation. Along with market days, the institution of twice-yearly fairs persisted in Philadelphia even after similar trading days had been discontinued in other colonial cities. The fairs provided a means of bringing handmade goods from outlying places to would-be buyers in the city. Linens and stockings from Germantown, for example, were popular items.

Auctions were another popular form of occasional trade. Because of the competition, retail merchants opposed these as well as the fairs. Although governmental attempts to eradicate fairs and auctions were less than successful, the ordinary course of economic development was on the merchants' side, as increasing business specialization became the order of the day. Export merchants became differentiated from their importing counterparts, and specialty shops began to appear in addition to general stores selling a variety of goods.

One of the reasons Philadelphia's merchants generally prospered was because the surrounding area was undergoing tremendous economic and demographic growth. They did their business, after all, in the capital city of the province. Not only did they cater to the governor and his circle, but citizens from all over the colony came to the capital for legislative sessions of the assembly and council and the meetings of the courts of justice.