The bluff where Riverside Park sits towers over the plains and was frequented by both American Indians and early Euro-American settlers as a place to observe game and by travelers on an old road from central Missouri through present-day Southeast Kansas that crossed the Neosho River where the Oswego water plant now stands. In 1887, the Lady's Entertainment Society was formed to raise money to buy the land for a park, and after numerous fundraising events they purchased it in October 1887, despite its being described as overrun with scrub oak and brush and fit only for rabbits and snakes. On May 22, 1902, the land was deeded to the City of Oswego for the sum of $1. The property remained mostly unused until the 1930's, when the city chose to develop the park, building picnic shelters and issuing $15,000 in bonds for a new swimming pool, the second largest pool to open in Southeast Kansas. With labor provided by the Kansas Emergency Relief Committee, work began in 1934, and the grand opening of the park and its new swimming pool was held on June 19, 1935. The historic core of Riverside Park, encompassing about 17 acres, was approved for listing on the National Register of Historic Places on July 17, 2012, as part of the "New Deal-Era Resources of Kansas" multiple property nomination, and it was officially dedicated as a Historical Site during a special ceremony on September 28, 2013.