Lincoln Township is a township in Shelby County, Iowa. In the 2020 U.S. Census, there were 406 residents of the township, with 137 occupied dwellings, and 3 unoccupied dwellings.<Ref name="2020census">2020 U.S. Census Iowa Townships and Other Subdivisions Population, sos.iowa.gov</ref> The total area is 33.6 square miles.
This township was constituted on April 3, 1871, when it had a population of 129. It it bounded to the north by Westphalia Township, on the east by Center, on the south by Shelby and Fairview, and on the west by Cass.<Ref name="formation">Biographical History of Shelby and Audubon Counties, ch 2 (1889)</ref> The first white settler in what became the township was likely Jacob Bosley, who arrived in 1865, followed most likely by T.A. Long in 1868.
The township's population declined since the 1930 census (population 640) to 371 in the 2020 census, before rising slightly to 406 in the 2020 census.<Ref name="1960cs">1960 Census of Population - Advance Reports - Final Population Counts; Reports and Tables: Illinois Through Massachusetts, p. 69 (1960)</ref><Ref name="1960-70">[1970 census info], pdf p. 77</ref><Ref name="1930-50">Iowa 1950 Census report, PDF p. 19</ref><Ref name="2010census">2010 census</ref><Ref name="2000census">2000 Iowa Census</ref><Ref name="1990and2000">1990 and 2000 township census numbers</ref>