Originally, Marion County covered more than a third of the area of Kansas, including all the territory in the state south and west of the present northern and eastern lines of the county. The original location of the county was fixed by legislative act in 1860. It comprised less than the present area. The original boundaries were altered by an increase of territory on the west and a decrease on the south. In 1863, the legislature by special act fixed the boundaries to include all of southwestern Kansas. In June of that year, on petition of the citizens of the county, the governor restored the previous boundaries and ordered a separate organization of the county. The south-eastern border one mile "notch" with Chase County was established under unusual circumstances. A murder had occurred and Marion County didn't want to have the trial, so a section one mile wide and eighteen miles long was ceded to Chase County to ensure the murder had occurred there. The one mile strip of land remains in Chase County to this day. The present county boundary lines were decided upon in 1872 and contain twenty-four townships.