Alexander was founded in 1869 as a trading post and is the oldest town in Rush County, being settled five years before the county was created. The trading post, called "Harvey's Ranch", was established in 1868 by Alexander Harvey, a soldier in General Custer's 6th Cavalry during his 1868 campaign, and in whose honor the town is named. The post was located on the north bank of the Walnut Creek on the Fort Hays-Fort Dodge Military Trail and served as a refuge for cavalry, freighters, surveyors, hunters, trappers, traders, and travelers, as they worked their way along the trail. The stockade that surrounded the post was a protection against renegade Whites, Indians, and other prairie wildlife.
The first settlers were the J. C. Young family who came in 1872 from Pennsylvania. The first schoolhouse in the region was made of logs from the trees along the Walnut Creek. Public meetings, Bible school and prayer meetings, were conducted in this school house. The first mail service was carried by train to the "end of line depot" where it was transferred to stagecoach and carried along the Fort Hays-Fort Dodge Trail to Alexander.
In 1886 the Santa Fe Railroad was nearing completion in Rush County. At that time, Alexander was situated on the north side of Walnut Creek but after a second railroad survey, Alexander relocated on the south bank of the Walnut and soon businesses flourished in the new location. The year 1909 marked a general building boom with new people moving in from the Eastern and Middle States. The town continued to grow until after World War II.
In 1916, the first consolidated public school in Rush County came to be with construction of the Alexander Consolidated School. Comprised of the Alexander and surrounding districts, the new school, a beautiful brick and limestone structure, housed eight elementary grades and a high school. An addition in 1930 housed a gymnasium with opera-style stadium seating, a large stage, and locker rooms. For a period of time, it was the largest gymnasium in the county.
Today, a plaque located on the west edge of town commemorates the location of Alexander Harvey's Trading Post and the Fort Hays-Fort Dodge Military Trail.