How did Mr. Beale know that Maniac didn't live where he said he did?

From the text:

Mr. Beale stopped, but he didn't let Maniac out of the car. He looked at him funny. Mr. Beale knew what his passenger apparently didn't: East End was East End and West End was West End, and the house this white lad was pointing to was filled with black people, just like every other house on up to Hector Street.