Olathe, the county seat of Johnson county, is located very near the geographical center, at the junction of three railroads—the Atchison, Topeka & Santa Fe, the Kansas City, Clinton and Springfield and the St. Louis & San Francisco—26 miles southwest of Kansas City. In the spring of 1857 Dr. Barton with a party came to lay out the town. With him was a Shawnee Indian, and when the location of the future town was pointed out to him he exclaimed "O-la-the!" the Indian word for beautiful, which was adopted for the name of the future city. Upon the completion of the survey of the town, building was at once commenced. Dr. Barton and Charles A. Osgood built the first house early in the spring of 1857. It was a rude structure of rough lumber, located near the site where the Olathe House was afterwards erected, and served a manifold purpose as grocery, drug store, dry goods and farm implement house, and also as the first hotel. Among the pioneer settlers were Henderson Boggs, Jonathan Millikin, Charles Mayo, J. B. Whittier, Charles A. Osgood, S. F. Hill, C. M. Ott, J. H. Blake and John P. Campbell. Jonathan Millikin built a fine house close to the town and the next year married Emily L. Whittier, the pioneer woman settler of Olathe. J. B. Whittier opened the first regular hotel, known as the Union House.

Olathe was incorporated in 1857 under a charter from the "Bogus Legislature." On Sept. 14, 1859, its first board of trustees was appointed, consisting of Jonathan Millikin, J. T. Barton, S. F. Hill, A. J. Clemmens and L. S. Cornwall. Some doubts existed as to the legality of the incorporation and it was re-incorporated in 1868 as a city of the third class, with the following trustees: R. E. Stevenson, B. F. Pancost, Charles Sennet, G. F. Hendrickson and William Vickers. By 1870 the population had increased to over 2,000 and Olathe was incorporated as a city of the second class. The election for city officials was held in April of that year, when William Pellet was elected mayor. The stone school house was erected on Lulu street in 1868, at a cost of $10,000, but some 15 years later the school population had outgrown this building and bonds to the amount of $15,000 were voted for the erection of another building, so that today Olathe has one of the best public school systems in the state. Olathe College was established in 1873, which was a prosperous institution for several years. The state legislature located the Kansas Institute for the Deaf and Dumb at Olathe in 1866. The leading churches are the Catholic church, established in 1864; the Old School Presbyterian, organized in 1865; Congregational, 1865; Methodist, 1869; Reformed Presbyterian, 1866; and the Baptist church, 1870.

The Olathe Herald, the first newspaper in Johnson county, made its appearance on Aug. 29, 1859. On Sept. 6, 1862, its office was destroyed by Quantrill. In 1861 the Olathe Mirror was started by John Francis; the next year W. H. McGowan began to print the Western Progress, and on July 24, 1879, the Olathe Gazette made its first appearance.

Olathe was one of the early manufacturing towns of the border counties. The Olathe flour mills were built in 1869 by C. M. Ott. The Pearl mills were erected in 1880. Today Olathe is one of the most progressive towns in the eastern part of Kansas. It is an important shipping point, has many retail stores and mercantile concerns, public library, electric-lighting, telephone, telegraph and express facilities. waterworks system, the milling industry has increased and other factories have been established. In 1910 the population was 3,221.