[4] In 1867, plans for a seawall and a driving track and walkway were made and drawings for the park were obtained from Frederick Law Olmsted whose firm completed the work.

In 1884, Olmsted described Seaside Park as "a capital place for a drive or walk.... a fine dressy promenade.

[7][8] The addition of Fayerweather Island in 1911 and Barnum Field in 1936, coupled with landfill operations, increased the size of the park to its present total of 375 acres (152 ha).

Results include a realignment of roads, more parking and a new bathhouse on the west beach with bathrooms, showers and cabanas.

When the idea of Sunday concerts "for the benefit of the working people" was proposed in 1890, many neighboring residents opposed the plan, but Barnum, whose own home abutted the park, championed the cause in the local papers.

When there was talk of police interference at the first concert, Barnum told the band leader to come play at his home and that the grounds would be open to all who wanted to hear the music.

[10] In the 1930s, the Bridgeport WPA Orchestra, a statewide unit of the Federal Music Project, gave Thursday night concerts free to the public with amplification provided by the city.