Answer:
They are many and one, they wave and they drum, Used to cover a state, they go with you everywhere.
What is never used unless it's in a tight place?
It cannot be seen, it weighs nothing, but when put into a barrel, it makes it lighter.
I have rivers without water. Forests without trees. Mountains without rocks. Towns without houses.
In this place, people lie, people cry, and people ask why. In this place, people sleep, people weep, and people's solitude, they keep. What is it?
It rows quickly with four oars but never comes out from under his own roof. What is it?