Seapo, Kansas, was a rural community in Grant Township in Republic County. It was first established as Salt Marsh in 1866. A post office was established on July 9, 1866, which was the first post office in the county. It was also one of only three post offices between Manhattan, Kansas, and Denver, Colorado. The town was “well laid out on a level plain” but “without a tree or fence ornaments.” It was the oldest village in Republic County. The name changed from Salt Marsh to Seapo in June 1871.
Just north of the town was a three-story Seapo Mill, built in 1872 by A.W. Miller, who also operated the grist mill. The construction of the native limestone mill cost $12,000 and was financed by T.B. Hazen, who ran a store in Seapo. The mill was originally powered by running water but was later powered by a 45-horsepower steam engine. It ran “night and day,” and it took two tons of coal and one cord of wood to run the mill for 24 hours. The mill was capable of running five runs of burr stones with a capacity of 100 barrels of flour per day. The dimensions of the mill were 30 feet wide by 40 feet long by 28 feet high.
There were also three church organizations: Christian, Methodist, and Presbyterian, and a school building.
The post office was discontinued on September 25, 1889. The mill was converted into a house in 1898. There was a dock on the south side, but it was replaced with a porch when the mill was converted into a house by the Hazen family. For more than 75 years, the mill was home to members of the Hazen family. The house was abandoned in 1988 when the owner died, but the structure remains standing.
The abandoned townsite adjoins the Talmo Marsh Wildlife Area, an inland salt marsh. The now-extinct town was located two miles south of Wayne on the eastern edge of the Great Salt Marsh.