You Do Need power plug adapter while traveling from Tonga to United States of America (US) USA.

Here is Why You Need An Adapter

The outlet and plug type used in United States of America (US) USA are A and B and in Tonga is I. This is how they look like.

In Tonga, outlets of type I are in use.

Type I

In United States of America (US) USA, outlets of type A and B are in use.

Type A

Type B

I am from

going to