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

Here is Why You Need An Adapter

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

Panama

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

Type A

Type B

American Samoa

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

Type A

Type B

Type F

Type I