I heard a black person speaking a "click" dialect in Tucson, Arizona: what tribe or nationality speaks that ?

Answer 1

The Khoisan Language family contains South African click languages. The most well known are Zulu and Xhosa. Others are Ndebele, Swazi, Sotho, Hadza, and Sandawe. (Hadza and Sandawe are spoken in Tanzania. They are click languages, but they are not from the Khoisan language family)

It is reasonable to assume that they were from South Africa, but you cannot really tell. They may have been speaking one of the click languages of Tanzania.