Pottawatomie County, formerly a part of Riley, was organized by the territorial legislature of 1857 with northern and southern boundaries the same as at present; the western boundary 5 miles east of the site of Manhattan, and the eastern boundary extending 5 miles beyond that of the present. The county is the second from Nebraska and the third west from Missouri. It is bounded on the north by Marshall and Nemaha counties; on the east by Jackson and Shawnee; on the south by Wabaunsee and Riley, and on the west by Riley. The Kaw river forms the southern boundary, and the Big Blue the western.

The first white people to settle within the borders of the county were Catholic missionaries who went to St. Marys a few weeks preceding the immigration of the Pottawatomie Indians to their reservation, of which St. Marys was a central point. This was in 1848. The mission and a log house near it were built the same year. The Indians contributed to the erection of the mission school, which was 15 years in advance of the common schools. A band of Michigan Pottawatomies joined their tribesmen on the reservation in 1850. In 1853 the population consisted of the Catholic missionaries, a few traders, 5 government employees, and the following settlers: Dr. L. R. Palmer and his family, Alexander Peltier, Basil Germore, William Martell, Francis Bergeron, Antoine Tescier, J. B. Frapp, Robert Wilson and family, Joseph Truchey, Alva Higbee, O. H. P. Polk, Baptiste Ogee, Mrs. Zoe Durcharm, Mrs. E. A. Bertrand, Mrs. A. P. Bertrand and Mrs. Clara Bertrand.

Dr. Palmer, who came in Sept., 1850, was later a member of the first free-state territorial council and of the convention which framed the Wyandotte constitution. His son, Francis X. Palmer, born March 17, 1851, was the first white child born in the county. James Graham, who came with the priests, was probably the first white settler. Robert Wilson was the first man to stake off a claim and he built the first house outside of the reservation on the site of the present town of Louisville in 1853. The first Indian agent was Luke Lee, stationed at St. Marys. The last was Dr. Palmer in 1870.

In Feb., 1857, after the founding of the new county, St. George was made the county seat, and Gov. Geary appointed the following officers: Robert Wilson, probate judge; J. L. Wilson, sheriff; George W. Gillespie and Charles Jenkins, commissioners. The commissioners met at St. George and divided the county into four townships, Pottawatomie, St. George, Blue and Shannon. They also appointed L. R. Palmer, county clerk; Josiah D. Adams, treasurer; J. A. J. Chapman, surveyor; W. L. Seymore, coroner; and James S. Gillespie, assessor. During the next two years Vienna and Louisville townships were organized. In 1861 an election for the location of county seat was held. Louisville won by a majority of 12 votes and the next year the legislature declared it the county seat. It continued as such until 1882, when another election gave the honor to Westmoreland. By that time 15 new townships had been organized, making 21 in all.

The public lands were surveyed in 1857-58, and the settlers began to get clear titles to their farms, which they had been occupying and improving for several years. During the war Pottawatomie contributed her quota of soldiers for the defense of the nation, as well as taking care of her own troubles.

The population in 1860 was 1,529; in 1870, 7,848; and in 1910 it was 17,552. The assessed valuation of property was $32,573,774, which would make an average of $1,944 for each person. The total value of farm products was $5,279,294, of which field crops amounted to $2,804,778, and animals slaughtered to $2,196,761. The wheat crop sold for $35,088, and the corn for $1,693,629. Other important farm crops are sweet and Irish potatoes, oats, Kafir corn, sorghum and alfalfa. The fruit trees of bearing age numbered 150,000, of which 90,000 were apple trees.

The general surface is rolling, with bluffs along the Kansas and Big Blue rivers, in which limestone is extensively quarried for building purposes. Bottom lands average 2 miles in width and comprise one-fourth of the whole area. A good quality of gypsum is found along the water courses, especially at the mouth of Spring creek. Potter's clay is found in the southern and central parts of the county. There are thin veins of coal in the east and south which have received little attention. There is said to be a mineral spring of medicinal properties at Onaga. Besides the Big Blue and the Kansas rivers, which form the western and southern boundaries, there is the Vermillion flowing south through the eastern portion of the county and emptying into the Kansas. Its tributaries from the west are French and Mill creeks, and the tributaries of the Big Blue are Spring creek with eastern branches, Four Mile as a western branch, Shannon, Carnahan, McEntire, Cedar and Elbow creeks.

Pottawatomie county is well supplied with railroads to handle her products. The main line of the Union Pacific crosses the extreme south following the north bank of the Kansas river, the Topeka & Marysville branch of the same road is extended to Onaga and is in process of construction northwest from that point. The Leavenworth, Kansas & Western branch of the Union Pacific enters in the northeast and crosses west to Elaine, thence southwest into Riley county. The Kansas, Southern & Gulf operates a line from Blaine to Westmoreland. There are 98.23 miles of track in the county. There are 120 organized school districts in the county and several high schools. St. Mary's College at St. Marys is one of the leading Catholic educational institutions in the West. There is also a Catholic parochial school at that place, an Evangelical school at Belvue, and St. Luke's (a German Lutheran school) at Onaga.

The county is divided into 23 townships: Belvue, Blue, Blue Valley, Center, Clear Creek, Emmett, Grant, Green, Lincoln, Lone Tree, Louisville, Mill Creek, Pottawatomie, Rock Creek, Shannon, Sherman, Spring Creek, St. Clere, St. George, St. Marys, Union, Vienna and Wamego. The towns and villages are: Arispie, Belvue, Blaine, Broderick, Emmett, Flush, Fostoria, Garrison, Havensville, Holy Cross, Laclede, Louisville, Moodyville, Myers Valley, Olsburg, Onaga, St. Clere, St. George, St. Marys, Springside, Wamego, Westmoreland and Wheaton.