I assume that you are asking about Ira Berlin's four passages from his book The Making of African America. If so, the four passages are:
- The Middle Passage or Transatlantic Passage. Here, slaves were brought from Africa to the Americas.
- The Passage to the Interior. This is the passage in which slaves were moved from coastal regions to inland cotton areas. This happened in the early 1800s after the invention of the cotton gin had created "King Cotton."
- The Passage to the North. This is what happened in the 1900s, particularly around the time of the two world wars. Here, millions of African Americans moved from the rural South to the urban North.
- Global Passage. Here, Berlin is talking about a voluntary migration of Africans or people of African descent to the United States. This is the process in which immigrants are coming to the US from Africa and from the Caribbean.