Delta City was first acknowledged as Aiken. It was a small railroad switch or siding on the railroad system between Los Angeles and Salt Lake City. The nearby towns wanted to farm the land of what is now Delta, but in order to do so they needed to develop a way to irrigate their crops and keep a steady supply of water year round. In 1905, Aiken became Melville.
In 1906, Millard County held a convention to develop plans for irrigation and a dam. It took the collaboration of multiple irrigation companies to get permanent water storage set up. The dam even washed out a few times. The first house in Melville was built in the spring of 1907. Free land was advertised all over the United States, on the condition that the new owner be willing to “take up” a forty-acre plot. The plots of land were drawn out of a hat. A lot of people came to farm and ended up having to live in tents until they could get their homes set up. Since there were no trees in the grease-wood covered Melville, lumber had to be hauled in from Oasis. The United States Postal Service required that Melville change its name in order to get an official post office as Melville was too similar to another town in northern Utah. Melville was changed to Burtner in 1908 and the Burtner Post Office was established that year on January 18. Shortly after, on September 12, 1911, Burtner was changed to Delta.
In 1913, Millard County adopted a resolution stating the Delta was incorporated as a City. In 1917 Millard County Commission adopted a resolution that approved the dedication of the Delta Town Site Plat "A" which was amended and rededicated the following year. On July 29, 1940 the governor of Utah, Henry H Blood declared Delta to be a city of the third class rather than a town. In 1942 construction on the Delta Airport began. On September 11, 1942 Topaz Internment Camp was occupied by Americans of Japanese ancestry. It was occupied until October 31, 1945. Delta City was presumed to be incorporated effective, November 30, 1979.
The Delta Melville and Delta (DMAD) dam spillway failed on June 3, 1983 and the resulting flood flooded Deseret, Oasis, and Sherwood Shores.
The year 2007 was an eventful time. Delta was awarded the Guinness World Record for the world's largest bunny hop. There were 3,841 participants. Also, a new water storage tank and well were installed in order for the city to meet arsenic regulations because of an unmandated requirement by the U.S. Department of Environmental Quality. The tank has a two-million gallon capacity. The Great Basin Museum moved to their new building May 26, 2012. A new high school was completed in the fall of 2013. The Delta Community Center opened March 29th 2014. The Topaz Museum opened shortly thereafter too.