People will watch his speech at U.S. embassies in the region while others will participate online via Twitter, Facebook and the White House blog. The visit is historic because it is the first time it will involve social media and because Obama is visiting Ghana rather than Nigeria, the western African powerhouse, and Kenya; his father's birthplace.

Using campaign-style techniques, Obama's message during his first venture into sub-Saharan Africa will consist of the so-called "watch parties" at embassies, broadcasts in "public spaces" and streaming live content on social-networking sites. In Kenya, the U.S. embassy has organized a watch party at the Intercontinental hotel.

The U.S. government has set up a site where users can register to receive SMS (Short Message Service) updates about Obama's visit and send messages and comments. The visit organizers invited users to pre-send SMS messages via MXit, a South African SMS service with 14 million users worldwide.

"We are very proud to have been asked to be part of a campaign to better understand and engage with African youth," said Herman Heunis, MXits founder and CEO.

Obama's visit has generated a lot of debate, because he is insisting on visiting countries that show good examples of democracy and good governance, sending stern messages to countries like Zimbabwe and Kenya.