Formal:
* Habari! Karibu Amerika! (Ha-ba-ree! Ka-ree-boo Ame-ree-ka!)
Informal:
* Jambo! Karibu Amerika! (Ja-mbo! Ka-ree-boo Ame-ree-ka!)
Explanation:
* Habari (formal) and Jambo (informal) both mean "Hello" in Swahili.
* Karibu means "Welcome".
* Amerika is the Swahili word for "America".
You can choose either the formal or informal greeting depending on the situation and your relationship with the person you are greeting.