The American Board followed with many other appointments in rapid succession. Revs. Ira Tracy and Samuel Wells Williams (1812–1884), followed in 1833, settling at Singapore and Macau. In the same year Revs. Stephen Johnson (missionary) and Samuel Munson went to Bangkok and Sumatra. There were four great centers from which smaller stations were maintained. These were Fuzhou, in connection with which were fifteen churches; North China, embracing Beijing, Kalgan, Tianjin, Tengzhou, and Baoding, with smaller stations in the various districts of the center missions; Hong Kong; and Shanxi, with two stations in the midst of districts filled with opium cultivation and staffed by missionaries of the Oberlin Band of Oberlin College.