The township of Union was first composed of the whole of Union County. Other townships were organized from time to time and detached until there remained the current township boundries. The incorporation of Afton in 1868 took out the center of the township. The name came to the township by first being co-equal with the county in territory. As late as 1857 all the rest of the county voted in Afton.
With the exception of two log cabins built in 1852 on section 14 by John Edgcomb and Samuel Starr and two similar structures in 1854 by James Thompson and James Husband on section 25, all other improvements were commenced in Afton.
There is little history for the early days of Union Township separate from that of Union county and the town of Afton. After the incorporation of Afton, the township elections continued to be held at Afton until 1883 when at the March term of the board of county supervisors, George S. Miller and ninety other legal voters being a majority, residing outside of the corporate limits of Afton, petitioned for a division, making the territory outside of Afton an independent township.
Among the early settlers in the township outside of Afton were Joseph Peck, D. A. Wycoff, A. Dickenson, Staneil Moffitt, Solomon Moffitt, Ed Hayward, A. Rogers, James Thompson, James Husband, Hintin Lary, John Ickis, J. F. Ickis, Henry Robb, Dr. James Lewis, E. M. Buckley, Hiram Westover, and Cyrenus Ames.
On the first day of October 1854, Edward A. Temple of Chariton, Iowa entered the southwest quarter of section 16 and proceeded to plat it into lots. On 14 February 1855, he recorded a plat of the town. Prior to the recording, Temple and his wife executed to Union county a warranty deed to all the even numbered lots on the plat. The name, Afton, was given to the town by Mrs. Temple, having chosen it from one of the songs of the Bard of Avon, “Flow Gently, Sweet Afton”.
The county seat of Union County was located in Afton by a commission appointed for that purpose, February, 1855. Later that year, eight log dwellings were erected. In 1856, small frame dwellings and business houses were built.
Among the first settlers of the town were J. W. Alley, Reuben Riggs, Jesse B. Berry, Thomas Tall, J. S. Elliott, J. B. White, T. M. Robinson, David Fife, Charlie Barlett, W. M. Locke, C. B. Holler, Joseph Norris, J. A. Blanchard, W. B. Davis, John Cantrill, James Lewis, and Mrs. Sarah Collings.
The first courthouse and first school-house was built in 1857. The first stores were owned by Dr. Blanchard, drugs and medicines; David Fife, J. S. Elliott, J. B. White, John Cantrill, general stores. The supplies for these businesses were brought by wagons from St. Joseph, Missouri. The Afton Eagle, published by Morris and Ryan, in 1859, was the first newspaper published in the county. Information from 1908 Union County History by George A Ide.
Greenlawn Cemetery, Norris Plot, Rollins Plot, and St. Edward's Catholic Cemetery are located in Union Township.