Menlo is a small unincorporated community in the Willapa Valley of Pacific County, Washington, United States. It was settled in 1851 as a donation land claim. Menlo was named Menlo Park in 1893 when the Northern Pacific Railway line was laid down through the Willapa Valley. It was shortened to just Menlo when the sign was cut in half. Menlo today is home to a general store and post office, the Pacific County Fairgrounds and a secondary/high school — Willapa Valley High School.