Nashville is the capital of Tennessee.  It is also the most populated city of Tennessee.  
That's interesting. What's the population?
It is about 660,000 people.  Nashville is located in the north central part of the state, right near the Cumberland River.  
I've never heard of the Cumberland River. How wide is it?
Its width varies, but it is nearly 700 miles long.  The river drains though Kentucky and Tennessee.
Wow! 700 Miles?! Where does it start?
It begins in Kentucky with major tributaries all around.  The city of Nashville hinged upon that river, which explains its populous growth.  With all regions right around Nashville, including Murfreesboro and Columbia, etc., ... the population is nearly 2,000,000.