Here is a blog post from Michigan State University about earthworms

The last ice age wiped out the earthworms in North America. Other composters replaced the earthworms.

European settlers introduced the earthworm and it has caused horrible problems for the Michigan forests.

I live in Utah, the native composters produce a rich loam.

BTW, Utah has had some problems with invasive worms. A few years back Kevin Bacon was in a documentary about invasive worms down in Perfection Valley.

!ALIVE