What does the cascades border?

the main ridge line of the cascades forms several continuous county borders in Oregon

running from south to north

between Douglas lane linn Marion clackamas & multnomah counties to its west

&

klamath deschutes Jefferson wasco & hood river counties to its east

&

after a gap

the same ridge line also forms several continuous county borders in Washington

running again from south to north

between Lewis pierce king snohomish skagit & whatcom counties to its west

&

yakima kittitas chelan & okanogan counties to its east

so it alone borders 21 counties in all

& in fact forms no fewer than 18 of their mutual borders

& that total accounts only for the main ridge line & the most important geopolitical borders upon it

in addition there are many other ridges of the cascades

which form many less important boundaries as well