为什么说Moon river 是 wider than a mile?

Moon river, wider than a mile
Im crossing you in style some day
Oh, dream maker, you heart breaker
Wherever youre goin, Im goin your way

Two drifters, off to see the world
Theres such a lot of world to see
Were after the same rainbows end, waitin round the bend
My huckleberry friend, moon river, and me

(moon river, wider than a mile)
(Im crossin you in style some day)
Oh, dream maker, you heart breaker
Wherever youre goin, Im goin your way

Two drifters, off to see the world
Theres such a lot of world to see
Were after that same rainbows end, waitin round the bend
My huckleberry friend, moon river, and me