Why is the mississippi river more of a highway than the amazon river?

Development is an important factor to comprehend the socioeconomic situations in rivers. Economic state of the Midwestern USA is much more developed than Amazon River region, that makes the Mississippi River more of a highway while there is not much going on in Amazon River.

Answermost of the time it would be ground into fine sediment,and sometimes they are carried away from the original location;

Answer (d) may increase or decrease porosity through dissolution or deposition;