During Johnston’s administration, the procedure in elections and elections contest was amended and written in more detail. The City´s population had about doubled from the 4,000 in 1820, so it was decided to divide it into four wards instead of the three set up under the first mayor. An ordinance was passed regulating the revenues and taxes of the City and setting out the duties of the assessor, collector and register in detail. One of the City´s first parking regulations made it unlawful to park carriages on the street overnight.

Johnston was born in Maryland in 1774. As a government trader with the Indians, he met and married the daughter of Indian Chief Keokuk. Following her death, he married Mrs. Lucy Honeywell Gooding in 1831. Under the care of his second wife, his three Indian daughters became prominent in St. Louis society. Johnston came west in 1808 as a government trader with the Sauk and Fox tribes. In 1818 he officiated in the purchase and distribution of $30,000 worth of presents to the 19 Indian Tribes who made peace at Portage des Sioux, in St. Charles County.

Mayor Johnston died June, 1854, at the age of 80 and was buried in Calvary Cemetery in St. Louis.