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How many people live in Cascadia? (Spoiler: 21M. But let’s break it down.)

sightline.orgTwenty-one Million Cascadians: An Overview | Sightline InstituteWho is Cascadia? A new series on the bioregion’s people.

8/10/26, 3:45 pm1 repost20 likes

Andrew

@bikesnacks.bsky.social

Something got clipped here.

Sightline Institute

@sightline.org

We'll correct this—thanks for flagging!

Sightline Institute

@sightline.org

Cascadia is a bioregion. We mark the borders by watershed, stretching from the Rockies to the Pacific and from Alaska to California. Those aren’t political borders, which make them hard to tabulate.

Sightline Institute

@sightline.org

Resident Data Guy @jayleetx.com took up the task of counting the people who live here: all 21,561,819 (ish) of them.

And it's growing.

Unsurprisingly, the population centers are Cascadia’s largest urban areas. The top ten most populous jurisdictions are home to 10.8 million people, while the other half of the region is spread out across the other 165 jurisdictions. More data: www.sightline.org/2026/10/08/t...