You Do Need power plug adapter while traveling from American Samoa to Greenland.

Here is Why You Need An Adapter

The outlet and plug type used in Greenland are C, E, F and K and in American Samoa are A, B, F and I. This is how they look like.

American Samoa

In American Samoa, outlets of type A, B, F and I are in use.

Type A

Type B

Type F

Type I

Greenland

In Greenland, outlets of type C, E, F and K are in use.

Type C

Type E

Type F

Type K