there are no bridges across the entire width of the river. this is not because the river would be too wide to bridge; for most of its length, engineers could build a bridge across the river easily. for most of its course, the river flows through the amazon rainforest, where there are very few roads and cities. most of the time, the crossing can be done by a ferry, so there is no need to build a bridge. the manaus iranduba bridge linking the cities of manaus and iranduba spans the rio negro (a tributary of the amazon).