On September 27 of 1801, the captain of American Vessel Pacific Trader sent a batch of letters to Guangzhou from Macau, with the receiving address Si Xing Store, Zao Shi Street, Guangzhou (廣州鑿石街的泗興辦館). These documents proved that Zao Shi Street, Guangzhou (廣州鑿石街) is the existing Da Shi Street (打石街) which is located on Hog Lane (豆欄) of Thirteen Factory Street (Thirteen Hongs of Canton)(十三行). Through these letters, the appearance and function of a store (辦館) can be further recognized. Apart from their general function which was to deliver information, they also provide a detailed individual case for the postal history of 19th century Macau and Guangzhou, which contributed to the further study of the Maritime Silk Road and the relationship between Macau and Guangdong province.