Rainier (/reɪˈnɪər/ ray-NEER) is a city in Columbia County, Oregon, United States.

Rainier is on the south bank of the Columbia River across from Kelso and Longview, Washington.

Rainier was founded in 1851 on the south bank of the Columbia River by Charles E. Fox, the town's first postman.

First called Eminence, its name was later changed to Fox's Landing and finally to Rainier.

[5] For much of the last quarter of the twentieth century, Rainier was known to the rest of Oregon as home to Trojan Nuclear Power Plant, the only commercial nuclear reactor in the state, which supplied electricity to Portland and its suburbs starting in March 1976.

The reactor was closed periodically due to structural problems, and in January 1993, it was decommissioned after cracks developed in the steam tubes.

The closing of the Trojan plant precipitated a decline in the number of businesses in the city.

These communities include Fern Hill, Hudson, Alston, Apiary, Goble, and Prescott.

The Lewis and Clark Bridge spans the Columbia River, linking Rainier to Longview, Washington.

It is the only bridge, that spans the entire width of the river, between Portland and Astoria, Oregon.