The Linnton Plywood Association (LPA) was a cooperative worker-owned mill, one of the earliest in the region. It operated on the Willamette River in the Portland neighborhood of Linnton from 1951 to 2001, when it was a significant contributor to the local economy. At a time when the plywood industry was cutting jobs, LPA was listed in the 1984 edition of 100 Best Companies to Work for in America. The mill closed in 2001 after reduced timber harvests in the 1990s. The property was named as a Superfund site in 2000, and the mill’s structures were razed in 2017. The site is now a nature park where habitat has been restored for wildlife, including bald eagles and mink, and with riverside channels for migrating Chinook salmon and lamprey. It is now off-limits to human use.

Linnton Plywood stood on the original site of the Clark and Wilson Lumber Company (C&W), founded in 1905. Orange Marcus Clark (1851–1929), his son Wilson Warner Clark (1878–1968), and his brothers-in-law John Wilson and Charles Wilson built a sawmill southeast of the present-day Linnton Plywood Mill complex. A planing mill stood south of the C&W sawmill near the Northern Pacific Railway tracks. Drying kilns and extensive wharves, planked drives, and ten-to-twenty-foot-high piles of lumber were stacked north and south of the mill, with mill ends and rejected lumber stored on the surrounding lowland. By 1924, large lumber sheds had been built to the north.

In 1907, the company purchased 10,000 acres of timberland near Goble, an unincorporated community on the Columbia River near Rainier. The Oregon Journal cited this purchase as one of the largest deals in Columbia River timberland ever made. Over the decades, the company continued to amass timber holdings and logging railroads and merged with other lumber companies. It logged extensively in the Nehalem Valley, which contributed significantly to the local economy in that region. By 1942, the lumber company had become one of Columbia County’s biggest taxpayers. The C&W’s holdings were sold to the Crown Zellerbach corporation in 1945, but by the mid-1940s the lack of an available supply of timber forced the mill to close. A fire at the mill complex in 1947 destroyed most of the property, except for some drying and equipment sheds and the dock area on the river.

In 1951, the Linnton Plywood Association incorporated with John J. Oxley as manager and leased the site of the former C&W company, which was then owned by the Spokane, Portland & Seattle Railway. Stock shares were initially advertised at $5,000 per share with the goal of acquiring 400 workers with experience making plywood. The February 25, 1951, Oregonian described the organization as the "first full cooperative under Oregon law for its type of manufacture." In September that year, the LPA completed construction of the new plant and began making plywood veneer. An average of about 250 shareholders worked at the mill throughout the company’s fifty years of operation.

Association mills produced high-strength material such as plywood and other wood-composite products, including T1-11, commonly used for construction (as siding for residential structures) through the second half of the twentieth century. Within a year, the plant boasted an annual capacity of 36 million square feet of 3-ply, 3/8-inch Douglas-fir plywood, with one lathe, one dryer, one cold press, and one hot press in operation. By 1970, LPA had the capacity to produce 7 million feet of 3/8-inch, 3-ply plywood and T1-11 and V-groove boards, with facilities containing two lathes, two dryers, two hot presses, and three glue spreaders. LPA purchased the property from SP&S Railway in 1971, and by 1977 the mill had added a dryer to the facility and Plyform panels to its production line, increasing its monthly capacity by 1.5 million feet.

Beginning in the mid-1970s many plywood mills across the state closed their operations due to a national depressed housing market, the high cost of raw timber, and the export of unfinished lumber to Japan. LPA board members voted to shut down the plant for a week in late August 1974, but they were able to open again quickly. At that time, Oregon accounted for 47 percent of the nation’s plywood productions and more than half of the 36,000 workers in the industry. But by the early 1980s, the number of co-op plywood mills in Oregon and Washington had diminished from 24 to 11. Only three mills remained in Oregon, including LPA (the other two were located in St. Helens and Astoria), down from 43 plywood mills in Oregon in 1953. The June 2, 1981, Oregonian reported that LPA was one of the consistently strongest co-ops, with 189 owners of the company working at the mill with an additional forty nonowner workers. LPA had become successful by investing in new equipment and mill improvements to keep up with changes in market demand and technology.

Beginning in the 1990s, the mill experienced financial trouble when timber yields were significantly curtailed by reduced harvests on federal timberland to protect endangered species, such as the northern spotted owl. The mill tried to accommodate the change. In 1992, LPA began importing veneer sheets, reducing the need for raw timber and the use of the log transfer, core mill, and barker machine that prepared logs to be processed into plywood.

In 2000, the Environmental Protection Agency designated the Portland Harbor, which included the twenty-six acres of LPA mill grounds, as a Superfund site. A Department of Environmental Quality investigation found significant levels of phenol-formaldehyde resin, sodium hydroxide and petroleum hydrocarbons at the site—chemicals used in making plywood. The LPA board and membership voted to liquidate the business, and $2.6 million was distributed among co-op members.

The mill closed in 2001, and RestorCap began the cleanup of toxins in 2015. In 2019, the Linnton Mill Restoration Project, with oversight from the Portland Harbor Natural Resource Trustee Council, restored the site as a park for wildlife habitat and provided an overlook where visitors can walk to view the restoration project.