Journey to Jo'burg

This term we were reading a novel called Journey to Jo'burg. It is a story about when black people have less freedom then white people. Black people have to carry a pass  and white people don't need to carry a pass. Why is the book title call Journey to Jo'burg because Naledi and Tiro need to get to their mum. She lives 300 km away. The need to walk to help their little sister Dineo so she doesn't die because she has a fever.