Mayor Thomas advocated City purchase of the gas works but was unable to bring this about. He did see his program for the improvement of public health enacted. Further development of the sewer system included provision for the Mill Creek, Rocky Branch and Arsenal Street sewers. He took the leadership in establishing a new waterworks system. In 1867 the construction of a plant began at Bissell´s Point. The East Grand Water Tower was a part of the whole project; it was completed in 1870. Cholera had broken out again in 1866. The mayor appointed sanitary committees in each ward. The mortality rate decreased shortly thereafter. In March 1869, the state legislature authorized the mayor to appoint a new board of Health. This new board organized and started its work on March 16, 1869. The present house numbering system was approved by Mayor Thomas on December 18, 1865. North and south streets were numbered from Market Street. East and west streets were numbered from the wharf. Each block west, north or south, represented one hundred numbers, as distinguished from the old system where numbers had been assigned without regard to blocks.

Mayor Thomas had come to St. Louis in 1825 and opened a small bank, the first in the City. His assets at the start were $270 in cash and an eastern credit of $3,000. In 1838 he entered partnership with L. A. Benoist in a more extensive banking business. This partnership was dissolved in 1850 and Mr. Thomas retired to private life. His first marriage was to a daughter of Curtis Skinner of St. Louis. He was married a second time, to Miss Susan H. Hackney, and they had one daughter.

Mayor Thomas took great interest in helping to develop Tower Grove Park from the land Henry Shaw and given the City. He was a member of the Park’s board of commissioners throughout the rest of his life. He died September 26, 1874. Burial was in Bellefontaine Cemetery.