The Puget Sound Primo catalog uses Library of Congress Subject Headings to help users find more books on a particular topic.  In the case of the history of the West, several subject headings may be used, depending on the focus of the work.

Here are a few examples of relevant subject headings, but there are many, many more:

• West (U.S) -- History
• Columbia River -- History
• Natural history -- West (U.S.)
• Indians of North America -- Northwest, Pacific -- History