Sentence:  The Central Lowlands is often referred to as the heart of America — and with good reason: If we look at the names of the eight <WSD>states</WSD> with populations of 10 million or more, this region has three of them, Illinois, Ohio, and Michigan, more than any one of the other five. 
Meaning of the word marked with <WSD> tags:  A political division of a federation retaining a notable degree of autonomy, as in the United States or Germany.