Like many other early settlements around here, it was started before the middle of the nineteenth century. In the vicinity of Knox Grove settlers had rounded homesteads in the late 1830s, and log cabins broke the monotonous expanse of the prairie around the present little community in the early 1840s. As one more township carved out of Old Inlet, Sublette joins Lee Center to the North.
Bureau County bounds it to the South, with LaSalle County forming half of the eastern boundary.
The township is that part of Lee County, formally known as number 19, north of range 11, east of the fourth meridian p.m. Soon after the organization of Lee County in 1839, the west half of the township, then known as Hanno, was put with what was called May Township. This was known as the Bureau precinct, the pollsbeing at the home of Daniel Baird. The east part of the township was incorporated with part of what is now Brooklyn, with voting at Knox Grove. The inhabitants of Bureau precinct were eager to have the boundaries of the town correspond with those of the precinct.