"The Heritage County Atlas Reprints Volume 6, An Illustrated Historical Atlas Map of Jasper County, Mo" Published by Brink, McDonough & Co, 1876 shows that there was a Joplin Township in 1876. It was east of Galena Township and between Galena and Jackson Township. On the map it was in parts of both Range 33 and 32 in the East/west grid and Townships 27 and 28 in the North/South. (Don't get confused in "townships" for some reason the "real estate" maps showed numbered "range" values on the e/w direction and numbered "townships" in the N/S direction - so there were numbered townships as well "named" townships - the latter appear to be political, whereas the former were to identify "real estate") The n/s line separating Galena and Joplin Townships appears to be Joplin city's North Main street. The next township north of Joplin was Mineral. Joplin township included Webb City and Carterville.   Although this doesn't answer your question "Was Joplin TOwnship in existence in 1870?" I hope this helps John