The township of Franklin lies in the southeast corner of Marion County, being bounded on the north and west respectively by the townships of Warren and Perry, on the south by Johnson County, and on the east by the counties of Shelby and Hancock. The township is traversed diagonally from southeast to northwest by the line of the Cincinnati, Indianapolis, St. Louis and Chicago Railway. The principal stream is Buck Creek, which enters the township across its north line a short distance west of its northeastern corner, flows through the eastern part of Franklin in a general southward direction, nearly parallel with the eastern line, and leaves the township at a point near its south eastern corner, joining its waters with those of Big Sugar Creek in Shelby County. Wild Cat and Indian Creeks, Big Run, and several smaller streams are tributaries of Buck Creek which flow in a south east wardly direction through Franklin Township to their junctions with the main stream.

Another stream, which also bears the name of Buck Creek (sometimes called Little Buck Creek), and is a tributary to White River, flows from its sources in Franklin south west wardly into Perry township. The surface of Franklin township is, like that of other parts of the county, nearly level in some parts, in others rolling, and in some parts hilly. The soil is, in general, excellent, well adapted to most of the purposes of agriculture, and the farmers working it are well rewarded for the labor they bestow upon it. The total population of the township in 1880 was two thousand six hundred and nine, as shown by the returns of the United States census of that year. Franklin was laid off and erected a township of Marion County by the board of county commissioners on the 16th of April, 1822, and on the same day, and by the same authority, Decatur, Perry, and Franklin were (because none of the three were then sufficiently populated for separate organization) joined together as one township.

This union of the three townships continued until the 12th of August, 1823, when Decatur was made separate and independent by order of the commissioners. Then Perry and Franklin remained joined together as one until May 12, 1824, when, upon petition, and it being made to appear to the commissioners that Perry and Franklin had each a sufficient number of inhabitants for separate organization, the board ordered that Franklin be taken from Perry, and that an election be held on the 19th of June following, at the house of William Rector, for the purpose of electing a justice of the peace, John Ferguson to be inspector of the said election.