riddle - Four Directions #3 - Where and what am I?

To the North, a mule may serve you in copper.
To the South, you may end up rich or a pauper.
To the West, "Keep it Weird" you may hear them mutter.
To the East, if you visit, bring plenty of butter.

I slithered for ages while the devils looked on. Where and what am I?

Four Directions #1
Four Directions #2

Answer

Maybe you are

Snake River?

To the North, a mule may serve you in copper.

The Moscow mule is a drink served in a copper mug, so this could point to Moscow, Idaho.

To the South, you may end up rich or a pauper.

To the south is Las Vegas with its gambling opportunities.

To the West, "Keep it Weird" you may hear them mutter.

To the west is Oregon, which is where you might hear the phrase "keep Portland weird".

To the East, if you visit, bring plenty of butter.

Not sure about this one. To the east are Salmon River Mountains, and you use butter to cook salmon?

I slithered for ages while the devils looked on.

Snake River slithers through Hells Canyon on the border of Oregon and Idaho.