In 1864, General Alfred Pleasonton defeated the Confederates in the Battle of Mine Creek near present day Pleasanton. This battle, involving 25,000 men, resulted in a Union victory which ended the threat of Confederate invasion in Kansas.

Pleasanton had its start in the year 1869 by the building of the railroad through that territory. It was named in honor of General Alfred Pleasonton, though the city name is spelled different.

The first post office in Pleasanton was established in August 1869.