Read it through once

It is a remarkable river in this: that instead of widening toward its mouth, it grows narrower; grows narrower and deeper. From the junction of the Ohio to a point half way down to the sea, the width averages a mile in high water: thence to the sea the width steadily diminishes, until, at the 'Passes,' above the mouth, it is but little over half a mile. At the junction of the Ohio the Mississippi's depth is eighty-seven feet; the depth increases gradually, reaching one hundred and twenty-nine just above the mouth.