Seneca, the county seat of Nemaha county, is located northwest of the center of the county on the St. Joseph & Grand Island and the Missouri Pacific railroads. It is also on the Nemaha river, 70 miles northwest of Topeka. It has a brick plant, an iron foundry, a cement block plant, a creamery, 4 banks, 2 weekly newspapers (the Tribune and the Courier-Democrat), high school, city library, waterworks and electric light plant, express and telegraph offices, and an international money order postoffice with five rural routes. The population in 1910 was 1808.

The town site was located by J. B. Ingersoll, who in 1857 staked off a claim which he called Rock Castle. A town company was soon afterward organized, the members being Samuel Lappin, Charles G. Scrafford, Royal U. Torry and Finley Lappin, and the town immediately platted was named Seneca. The first house, a double log structure, was built in the fall of the same year by Finley Lappin, who started a hotel in one end of it and rented the other end to Downing & Stewart for a grocery store. The hotel end was also used for an office by Samuel Lappin, register of deeds. A blacksmith shop, consisting of four poles covered with brush and a few boards over the forge, was put up by Levi Hensel, a correspondent of the New York Tribune.

The next year the Smith family, including John E. Smith and wife, two sons, W. H. and F. E. Smith, his brother Stephen and sister Addie Smith, made a valuable addition to the Seneca settlement. With them came Charles, George W. and Ezra Williams. John E. Smith built a hotel and erected a sawmill a mile from town. The machinery of the mill was hauled by an ox team from Atchison. Miss Addie Smith taught the first school in Smith's hotel in 1858. The next building was of concrete erected by Downing & Stewart. The fourth building of any consequence was a business block erected by the town company. The first child born in Seneca was Esther Hensel, daughter of Levi Hensel, in 1859. A town lot was conveyed to her by the town company.

The proximity of Seneca and Richmond, only three miles apart, created considerable rivalry. Up to the year 1859 Richmond received the overland traffic, which was very heavy at times. In order to divert this business to their town some of the prominent citizens of Seneca sowed oats on the road leading to Richmond for a considerable distance, which gave it the appearance of not being used. Seneca became a station on the Pony express from St. Joseph to San Francisco and also on the overland stage route and remained so until the railroads were built.

Seneca was incorporated as a city of the third class in 1870 and the following trustees were appointed: James P. Taylor, Charles G. Scrafford, J. B. Meyers, Abijah Wells and John F. McGowan. The first election was held in 1871 and resulted as follows: W. G. Sargent, mayor; George Graham, J. H. Peckham, John H. Larew, Jacob Meisner and Mathias Stein, councilmen. Abijah Wells was subsequently appointed probate judge.