You Do Need power plug adapter while traveling from South Africa 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 South Africa are C, M and N. This is how they look like.

South Africa

In South Africa, outlets of type C, M and N are in use.

Type C

Type M

Type N

United States of America (US) USA

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

Type A

Type B