_The Amazon._—Of the many navigable highways in South and Central America, the Amazon river is by far the most important. Nay, more, this river, which has a drainage area of 2,264,000 square miles, which has 10,000 miles of navigation for large boats, and which has a width of no less than four miles at a distance of 1000 miles from the sea, is in every respect the most extensive and remarkable river in the world. The average depth of the Amazon river is 42 feet in the upper portion, and 312 feet near to its mouth. The influence of the tide is observable at a distance of 400 miles from the mouth of the river, the usual current of which is about three miles per hour. The flood rise is from 42 to 48 feet above the lowest level. At a distance of 3000 miles from its mouth the Amazon is only 210 feet above sea level. Reclus has estimated the average discharge of the river to be 2,458,026 cubic feet per second.[123] _The Magdalena River._—The river in Columbia known by the name of the Magdalena has its rise in the Lagunas de las Papas (Potato Lake), and is one of the boundary lines of six of the nine States into which Columbia is divided. The river runs nearly due north from its source until it empties into the Carribean Sea in latitude 10° 59´ north, and 70° 58´ west longitude. The length of the river, measured on a meridian, would be 569 miles, but according to the best information available the actual length of the stream is about 900 miles. The Boca de Ceniza is the only mouth of the stream open to navigation, the depth of water on the bar here varying from 10 to 20 feet. It has been proposed to construct jetties at the mouth, so that it would be navigable to the largest ships frequenting this part of the world. A channel of 40 to 60 feet in depth can be found for a distance of about 20 miles inside the bar. Natural obstacles have compelled the navigation of the river to be divided into five different systems—the first, rafts and canoes from Bateas to Neiva; the second, steamboats, barges, rafts, and canoes from Neiva to La Noria; the third, steamboats, barges, and canoes from Caracoli to Barranquilla; and the fourth, barges, sailing ships, and small ocean steamers from Barranquilla to the ocean. It was not until 1847 that a really successful attempt was made to navigate the Magdalena by steam. Between that year and 1852 four steamers, of American build, were placed on the river. Now there are twenty-seven steamers regularly employed, besides a fleet of barges.