Part of the Columbia River System, the Port of St. Helens is 16 nautical miles downriver (28 kilometers or 17 miles direct) north of the Port of Portland. The Port of St. Helens is the seat for Columbia County, Oregon. The Port of St. Helens was known as Plymouth until its name was changed in 1850 for its view of Mount St. Helens to the north in the State of Washington. In 1889, the town of St. Helens was incorporated as a city. The 2010 US Census reported a population of almost 12.9 thousand people living in the Port of St. Helens.
In 1832, Boston's Nathaniel Wyeth built a temporary fort across the river from the future Port of St. Helens at Warrior Rock to trade with Native Americans. Creating a river port on the Columbia River, New Englander Captain H.M. Knighton founded what would become the Port of St. Helens in 1845.
In 1846, Knighton filed a claim on the land so that he could site the future Port of St. Helens. Believing that the new Port of St. Helens (called Plymouth at the time) would outshine the infant Portland as a fresh water port, he moved to the site in 1847. In 1853, the post office was opened in the Port of St. Helens. In 1889, the Oregon legislature incorporated the Port of St. Helens. The Port of St. Helens became the seat for Oregon's Columbia County in 1903, and the old courthouse was built from local stone in 1906.
The dominant industry in the early Port of St. Helens was logging. Farming was also important to the local economy. Manufacturing, focusing on wood products, later became a major source of income for the Port of St. Helens. The wood products industry continues to be a mainstay of the local economy.