Martin Luther King Jr targeted Birmingham, Alabama for a civil rights campaign because it had a reputation as the most segregated city in the South.
Birmingham is the most populous city in the US state of Alabama and is the county seat of Jefferson County. The city's population was 212,237 in the 2010 United States Census.
I am hoping that this answer has satisfied your query and it will be able to help you in your endeavor, and if you would like, feel free to ask another question.