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

Here is Why You Need An Adapter

The outlet and plug type used in Costa Rica are A and B 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

Costa Rica

In Costa Rica, outlets of type A and B are in use.

Type A

Type B