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

Here is Why You Need An Adapter

The outlet and plug type used in Pitcairn Islands is I 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

Pitcairn Islands

In Pitcairn Islands, outlets of type I are in use.

Type I