Sentence:  The central city <WSD>areas</WSD> , in other words , exhibit the two characteristics which violate the life principle of congregations of the major denominations : they have too few middle-class people ; they mix middle-class people with lower-class residents . 
Meaning of the word marked with <WSD> tags:  a particular geographical region of indefinite boundary (usually serving some special purpose or distinguished by its people or culture or geography)