Link

In the article linked below is a concise history, and some current news of human influences on our prairie and savanna ecosystems.

https://www.pacifichorticulture.org/articles/the-once-and-future-%E2%80%A8northwest-prairie/

Thanks to Pacific Horticulture Magazine and Daniel Mount for this article

The Willamette Valley, SW Washington, Puget Sound outwash prairies, and southern B.C. are all connected (geologically and topographically). This pops out on a foggy day as seen from a weather satellite: note the light gray fogged-in valleys all the way from Oregon to Canada!

In this satellite photo, on a day when fog fills up the Willamette Valley and Puget Trough (light gray areas), you can see the connected prairie landscapes in western Oregon and Washington mentioned in the article above