Complex sentence: He was president of the church's Northern States Mission from 1923 to 1928, when he took over as president of the mission home in Salt Lake City, Utah (predecessor to the Missionary Training Center).
Split into simpler sentences: He was president of the church's Northern States Mission from 1923 to 1928. In 1928 Taylor became president of the mission home in Salt Lake City, Utah (predecessor to the Missionary Training Center).