The plains are named for the Clatsop tribe of Native Americans who lived in the area at the time of the arrival of Europeans and European Americans by ship at the end of the 18th century and by land at the beginning of the 19th century.
These plains were developed from sand filling in the shoreline during the late Quaternary age. The northern portion is a result of the creation of the south jetty on the Columbia River built in 1885. Within the plain are several lakes including Cullaby, Sunset (Neacoxie), Smith, and Coffenbury. The latter three are filled by groundwater and not local streams or rivers.[3]
The first Presbyterian church was founded in 1846. Robert Morrison donated 10 acres for the church grounds, and then two more for a cemetery. The first church was built in 1850, but was destroyed by a windstorm in 1853. It was the first Protestant church built west of the Rocky Mountains. A new church was built and served until 1927, when the current building replaced it. The church is located east of Camp Rilea. The Pioneer cemetery established in 1846, making it the oldest in the county, is the burial place for many early settlers.
A community called "Clatsop Plains" was established and incorporated in 1870, primarily for the purpose of restricting cattle grazing along the sea ridge. This grazing was destroying the ridge grass and plants that prevented sand from blowing onto the nearby farms. As incorporated originally, "Clatsop Plains" extended from the Skipanon River to Seaside. An actual town eventually came into being about a mile north of Seaside, and was later absorbed into Gearhart. However, its early proximity to Seaside is probably why Seaside itself was sometimes referred to Clatsop Plains.[5]
The coastal grassy areas of Clatsop Plains was home to the endangeredOregon silverspot butterfly. Re-establishment efforts are continuing. (Speyeria zerene hippolyta).[6]